> When posts are removed on a social media platform, users may or may not receive an explanation. What kinds of explanations are provided? Do those explanations matter? Using a sample of 32 million Reddit posts, we characterize the removal explanations that are provided to Redditors, and link them to measures of subsequent user behaviors—including future post submissions and future post removals. Adopting a topic modeling approach, we show that removal explanations often provide information that educate users about the social norms of the community, thereby (theoretically) preparing them to become a productive member. We build regression models that show evidence of removal explanations playing a role in future user activity. Most importantly, we show that offering explanations for content moderation reduces the odds of future post removals. Additionally, explanations provided by human moderators did not have a significant advantage over explanations provided by bots for reducing future post removals. We propose design solutions that can promote the efficient use of explanation mechanisms, reflecting on how automated moderation tools can contribute to this space. Overall, our findings suggest that removal explanations may be under-utilized in moderation practices, and it is potentially worthwhile for community managers to invest time and resources into providing them.
Most people don't want their posts removed. Informing them of what rules they broke will help them about breaking those rules again, assuming they wish to not break rules, which it appears is generally the case.
I've had posts removed on subs for breaking some arcane rule before. On some subs it wasn't clear why, so I just never posted again. Others told me why, and even gave directions on how to avoid it again (usually flair related rules). It was easy to successfully post going forward on those subs.
One thing that seems to be an assumption is that the "company" needs to provide the explanation. I think it is even better if the user provides the explanation. The assumption a user can't provide it is probably because we've all seen Terms of Service agreements that are totally opaque.
Back in the day when I was doing a bit of admin work, I decided to simplify our TOS, and then when I had to block someone, I just kicked the ball back into their court: "If you would like your account restored, please point out in the TOS what rule you violated." It worked better than expected. People that cared enough about their access to the system usually figured it out pretty quickly, and we got the knowledge that they actually read the TOS to some degree. They got their account restored and that was the end of it. Repeat offenders at that point were willfully causing problems, so we just left them blocked.
Obviously this only works if a human can understand your TOS. Another interesting line of questioning might be "at what complexity level is your TOS useful in shaping behavior and where does it just become a legal shield."
I posted a video of me playing the piano on YouTube. I got a copyright notification, that I was playing the melody to a song that someone else held the copyright for.
What's the problem? Well, the melody was published in 1886 (133 years ago) under the exact name identified in the copyright claim. The composer died in 1901 (118 years ago). It is not under copyright protection in any jurisdiction! Now, I'm having to appeal the copyright claim... not to YouTube, but to ASCAP (the company who is claiming the copyright in the first place)!!!! In fact, because it was MY arrangement and MY performance and MY production, I own the copyright to that video in every way legally recognized! In my mind, this is THEFT... from ME!
My point is, if YouTube had not at least told me what I'm being accused of, there is no way that I would have figured this out! I haven't done anything wrong! Someone else (ASCAP, ICE_CS) is fraudulently claiming copyright!
Under your system, I would have to "invent" things to confess to.
Of course, now the problem is that I have no power in this situation. ASCAP must agree that they don't want to monitize my video, and they have no incentive to do that. I have no protection or recourse. :(
And, for anyone who's interested, this still isn't resolved.
In theory, you could sue ASCAP for damages and/or injunctive relief. Perhaps for libel, for grossly negligently communicating a false and disparaging claim about you to YouTube. Perhaps for tortious interference with business relations. But unfortunately, winning such a lawsuit likely requires an expensive lawyer, and sometimes you can only get as much justice as you can afford to buy.
In the lack of any clear infringement you can go through the terms of service and disprove every single one, and then come to a list of those that you're less clear about on a second pass and ask if you are mistaken about one of those portions and/or some other area that your conceptions are blind to.
At that level of genuine effort at the very least you've proven an attempt to understand (and maybe that the ToS got a little over-simplified in one or more areas, or that moderation was wrong).
It feels like the trend has been in the other direction. In most services I've interacted with recently, the service often doesn't even tell you that the content has been removed, let alone why. One example is Discord - if a mod removes a comment you made, it just disappears. You might try to repost it, thinking it failed to send. Similarly if you are removed from a server, it simply disappears from your list. This kind of thing is very frustrating/confusing - not that I expect a mod to necessarily provide explanation (though, that's nice) but at least the service saying "hey, that got removed" prevents me from trying to repost it.
The usual explanation involves spammers/scammers. Something like, if they know they got removed for violating some rule or the other, they can use that information to work around it in their next attempt. But for actual human users it can be very frustrating.
I assume the response "sorry, I looked at your TOS and don't see the problem" would not result in getting their account reinstated.
Now, every once in awhile we would get the "johnny logged into my computer and did it, not me." For technical and privacy reasons, we can't really block people, just computers. So, ya, they stayed blocked.
Is it perfectly fair? Nope. But simplifying a TOS definitely cut down on arguing with people, which was a win for us.
(of course, if everyone complains that they don't see the problem, then maybe it's the mod that doesn't understand the rules, or the rules are ambiguous)
At the very least, you should get a cut of the ad revenue your sub brings in. No technical reason they couldn't do that, and it would incentivize you to behave, as well.
It doesn't work just online: ask a children to solve some problem in a blackboard and then erase it without telling a thing, while leaving answers from other kids on it. You'll see that nobody likes to be "corrected" without an explanation.
"Violating Policy X" (where X can be something like Twitter's Rules, not necessarily something specific) is still a terrible explanation, but isn't nothing either. Vague enough spammers can't use it to game the system, specific enough that user's can guess they did something wrong.
E.g. i was blocked from facebook rencently and all it said is "you are inelligible, refer to our terms", but reading through them doesn't help at all
Automation-assisted, not automation everything.
I wasn't advocating for blanket terms that mean nothing. You need to provide the user with something meaningful.
>As a moderator, I will sometimes send a message to a poster whose post is removed. However, if it is "commercial spam," I don't bother because we both know why.
Sometimes redditors comment without understanding that they broke the rules. Sometimes redditors comment using spam and they fully know what they are doing. In the first case, a message to them to tell them why is helpful. In the second case, it's not.
I personally (as an active Reddit user), feel that the interaction with the mods there is always in a negative context. On /r/technology, for example, you can get ban without any specific reason and messaging the mods won't do anything.
A few weeks ago I made a silly comment in HN on a post that reached the front page.
My comment got a few downvotes and one of the mods sent me a message with what I did wrong.
I then went one step back, understood that I wrote something that is against the rules of HN and sent the mod an email with an apologie. He replied almost instantly.
That's one of the reasons I prefer HN over Reddit. It seems like the mods are not here to punish, but to create a healthy conversation infrastructure and to lead users who are not into the HN spirit yet, into the right path
As a result, growth doesn't happen here, only self validation. Try taking a nuanced view on privacy if you disagree.
It doesn't take many of those people to ruin the experience for others, and dang doesn't lift a finger A) because he's of the opinion that disagreement amongst users is bad for HN and B) the software running HN is old and not sophisticated enough to detect bad actors.
I had to abandon my other account recently because I'd get hit with 10-15 downvotes in the span of 3-5 minutes, multiple times a day as I was using the site. Many hours of minimal activity and then boom, minus 15 karma, all at once, corresponding precisely with the number of comments I had that were votable (less than a day old).
Not sure how to describe a nuanced point of view though, it's a point of view that loses critical fidelity when generalized. If the generalization falls into the "dissent" bucket, it's then given the above treatment by bad actors on HN, which has the effect of only allowing a single specific viewpoint to exist on HN, because "flagged" messages aren't displayed at all, and downvoted comments are literally hard to read via fading.
Dissenting opinions are basically just different from the majority. Anarchist opinions are like this, vegan opinions are like this. Fascist opinions are also like this. Just saying it’s dissent is not too informative.
There's all kinds of dissent which should absolutely be moderated away on a forum like HN.
How are people supposed to learn and improve without knowing told what they did wrong?
We used to give specific details for things (ie, price is going up because x). People INTENTIONALLY misunderstand, selectively pay attention, and argue endlessly.
Same thing with job interviews and hires. Imagine a potential hire for a client facing role with poor communication skills. If asked point blank about any areas of challenge in their application you might say this was a high pressure customer facing role and so communication skills, as described in job post, would be a big factor in the analysis. You might then be repeatedly followed up and both re-assured by them that they have excellent communication skills (with lots of bad grammar, spelling errors and terrible tone) and threatened for evaluating them on their skills in this area (which may overlap various protected classes).
People sometimes take the worst possible interpretation of any action and nitpick every explanation. Read hackernews for plenty of examples here.
In many cases, particularly if someone is not paying you - it's really not worth getting into it with folks who love to argue endlessly. They usually have FAR more time then you do, and if you have 20 people arguing with you an entire day can be lost dealing with them.
If you send an Email with some reasons, you're not required to spend hours defending your position. But giving some feedback is beneficial to the applicant and potentially also to yourself because you're forced to think about the reasons and keep a record which might also be useful.
You screen 100 resumes - you talk to 20 people. If you give quick feedback in the response for those 20, and do 5 positions in a year that's 100 quick pieces of feedback - I agree - would be totally useful.
Didn't have required license, communication skills weaker, not familiar with industry, not local to area etc etc. I could do these very quickly.
BUT it only takes ONE person tweeting and being offended by the response to cause huge problems even BEFORE you get to litigation risk and folks going back and forth on topics.
Imagine this - even job references in the US have gone to almost no content. "Giving a negative reference may expose the company to legal liability if the former employee does not get a desired job and decides to sue for defamation or slander. But providing a positive reference or failing to disclose potentially damaging information can leave the company open to legal liability (negligent referral) as well." - Result - again, just very little info is disclosed.
Sometimes folks have an axe to grind or lots of time on their hands (unemployed).
I used to work at a prominent venture capital firm where I started an initiative that required everyone on the investing team to respond to all inbound emails from founders, even if the reply was "Sorry, this isn't a fit for us." We tried for several months to respond with atleast 2-3 sentences about why we passed on companies if a founder ever asked. About 10% of founders said 'Thank you, that's useful' and moved on, another 10-15% straight up said "You're assholes" but moved on. The remaining majority were just incapable of understanding what we were trying to say since they were so sheerly blinded by their self-belief. Example, I remember emailing one founder of a poker game app back to say we didn't invest in gaming, only to receive an angry email saying poker isn't a game, it was a social activity. Thinking it would help, I replied saying 'Hey, thanks for the note. Really, our issue is that gaming apps and apps where the primary social activity is gaming, are very hits driven and we don't think we have the necessary experience ore desire to predict hits in this space.' He then proceeded to tell me why I did in fact have the skills required, even though literally no one on our team had consumer or gaming experience, and that I in fact also did have the desire to predict hits in this space - how could I not?_____"I was a VC after all"_____(direct quote)
A few months later, cold inbound emails that were passes went straight to archive...
Occasionally we would get questions back. There is a point at which you have to stop answering questions, though. We're not a tutoring service. At that point we'd just say something like, "We don't have any more detailed feedback other than what we've given you. Good luck on your job search" kind of response. We never got beligerent replies from candidates, but sometimes got them from recruiters.
The recruiters are the real problem because they will sometimes (some of them even often) demand "partial payment" for candidates that they thought were "good enough" but who we rejected. We had to write a few strongly worded "Our decision is final and we believe it is justified" letters to those recruiters. Saying that we won't accept any more candidates from the recruiters if they persist shut up most of them, but not all of them.
Eventually we gave up using recruiters anyway because they were essentially giving us random candidates. I think if you can find good recruiters and you can build up a good rapport with them, this kind of feedback is as useful to them as it is to the candidate. If you can't, then you are better off without them.
So, if anyone is wondering if it's worth doing, I would say that my experience is generally positive.
I think we’re at risk of building up the ultimate faceless and inhumane bureaucracy that works well in most cases but if you have bad luck then you have no way to clarify things unless you have a lot of money for lawyers or can raise a stink on social media.
Corporations are especially guilty of this, given how pathologically focused they are on shareholders. Often their cost-cutting verges on customer abuse: (e.g. https://news.ycombinator.com/item?id=21513556, for an example I recently read about).
The worst example of this I experienced was a purchaser buying parts that were not to the spec of the design and caused problems in the field. No one in engineering or support was told of this and it was discovered by our support team in the field. Then engineering had to step in and and say no, only to have to economically justify the increase in cost to meet the spec.
We hurt our customers, our product and lost future revenue due to a tarnished reputation. It is difficult to be proud of what you do when something like this happens. It is also unnerving to know that this could even happen in the first place.
All of this is due to short sited economics. Negative externalities be damned. Could it be better if we could measure negative externalities in dollars and cents? How does one economically measure trust?
As a general principle, conveying true information does not incur liability. In the specific case of job interviews, as long as the feedback is true and not of a legally discriminatory nature, there are no grounds to sue, and such a case would be thrown out by summary judgement. Any employment lawyer would laugh someone out of their office who came to them with a "case" like this.
I'm inclined to think it's primarily for the reasons mentioned elsewhere: avoiding back and forth arguments. Frivolous lawsuits from _pro se_ plaintiffs might be a minor consideration, but, as I said, those are easy to get thrown out, provided you're telling the truth and the reason isn't related to any protected classes in employment.
That said, providing explanations also invites arguments and hard feelings if they don't agree with your reasons or just think you're unfairly favoring someone else.
There are probably obvious things like "crash and burned on a whiteboard problem path-finding" or "requested more than was allocated for the position" (would be nice if possible compensation ranges were required in the posting); but past the obvious disqualifications (which candidates should get feedback on) there's that 'fits with the (a) team' phase. Having an 'exit value', even if generic / approved by legal, would be helpful for everyone including internal company metrics that might drive a better posting if the job isn't fulfilled.
Google has no legal obligation to provide you with Drive services, though. I believe they specifically disclaim any obligation in the EULA you agree to.
Google in particular seems to have a broad and well-established policy of refusing to talk to individual users, whether for bans or simple support, outside of a few specific categories. Someone did the math and decided that the cost of maintaining a review process and a customer service department was greater than the cost of the bad press from accidentally screwing over a few customers.
A few days ago there was a thing where someone had their Google account deleted without warning or recourse--including their Gmail--because they spammed emotes in someone's YouTube stream.
That's intolerable. I need to look into a convenient way to maintain a live local backup of my Google accounts; I've trusted Google for years to keep my data safe, and it seems like I've been naive.
It really is amazing how much power they have. In 19th century terms, if you're an ass to people at the tavern they can raid your home and burn all your personal documents and correspondences.
I think the lesson is when you rely on hosted services, you’re denying yourself the final say on who has access to your stuff and giving that say to someone else. Make sure you trust that entity.
That doesn't mean that the EULA is actually legally binding.
Nations with tougher consumer protections may actually allow recourse when Google decides to break a contract without what would be considered "good reason" under those same protections.
When I was first starting out, I found a job posting that I really wanted, so I applied and interviewed. I felt the interview went pretty well, but I got a call back that I wasn't what they were looking for. It was a small company, and the head of IT called me back to give me the bad news.
I really wanted the job, so I asked why. He told me I was too junior of a developer, and didn't understand OOP well enough. Being young and cocky as I was, I straight up told him I disagreed (looking back nearly 15 years, he was totally right). I didn't recall talking about OOP, per se, in the interview, and I had nothing to lose at this point, so I pressed the matter. I doubt it was OOP specifically that concerned him, and that it was more of a proxy for my inexperience. Either way, somehow I managed to get him to ask me about OOP over the phone. We talked a little about the vague concepts, and I have no fucking idea what happened, but he changed his mind and offered me the job. It was a great job, and I quickly learned how inexperienced I really was, but I grew a lot.
What am I getting at... in forums, you still _want_ them to participate, and come back. It is the opposite in an interview, you have essentially ended the relationship. Offering feedback starts the conversation again, and gives punks like me a chance to drag it out, disagree, and waste your time. We are just as likely to disagree with your assessment, if not more so, than to take it to heart.
Thank god he gave me another chance, I loved that job
Surprisingly enough, one of the places I least expected to get useful feedback from wasn't some small informal start-up, but a fintech giant Citadel. I already had a feeling about my weaknesses that led to failing their onsite, but their rejection email (with the feedback) helped me way more than that. Not only they pointed out those specific things I knew about already, they also pointed out a few others that I missed (that were all true) and gave me actually something useful to work with. Just wanted to express my gratitude for that, because I definitely (at least partially) attribute my improvement in those areas to that email.
In the end, it worked out for everyone. I spent 11 years there, finally leaving after we sold the company, and still keep in touch with many of them.
Why would they do an unpleasant task they don't really need to do?
It doesn't mean that their current behavior actually reduce risk.
When a company says, “we need to be opaque and evasive because liability” I immediately now assume the company is up to no good.
To shove this back into the 'online community' context, there are certain people who have no interest in learning what they're doing wrong; or even who fully understand that what they're doing is wrong, and have no interest in improving.
Examples: spammers, trolls, and the willingly-obtuse-slash-rules-lawyers (who are slightly separate from trolls, but are similarly un-educatable).
However, it is important to consider how bad actors will abuse your system if given the chance, because on the internet there will always be some trolls trying to burn your house down.
A community is better served by making gentle and public re directions that all can learn from where possible.
Because sometimes you're not hired because the person interviewing you can't imagine spending eight hours a day sitting across from someone who laughs like you do. We have increasingly open offices and then pretend that jobs are won and lost based on depersonalized notions of merit, completely without reference to the individuals who have the merit. Since we have to keep up the pretense of professionalism in the workplace, and can't, for example, walk over to someone and say that, while laughing is perfectly laudable, your specific laugh reaches into my skull and attempts to pith me by slow degrees, it's better to head those things off early.
Some of the biggest surprises and worst hires I've seen is people who are extremely slick in interviews. My mother has similar stories from working for a major financial institution for 35 years. She had consistently told me growing up over the years that half the time the best educated folks were all super slick in interviews and stellar on paper and then lazy as hell on the job.
The actually-good end up having to do precisely the covering-up you mention, because genuine and entirely fine attitudes and behaviors are, in interviewers' imaginations, often magnified to their worst possible extremes. It's very valuable information for a good employee to have that they need to cover up or avoid certain things in interviews that aren't actually a problem, because they do need to do that, and they may not realize how things that they think aren't a big deal and in fact are not are coming across in an interview context.
I write this as someone who is, I gather from feedback, pretty decent at that part of interviewing. Doesn't make it less gross-feeling and stressful.
Google's detection system is weak. Really everyone's is. So they use arbitrary ways to detect you have done something wrong. Sometimes it is a false positive. Sometimes they didn't think it through.
Like the guy who visited Iran and used his online account there only to get locked out because of being identified as belonging to a country on the export control list.
No point in giving that kind of feedback.
There is nothing new in this.
The forums were notable because they were VERY strict, but also every single removed post, suspension or ban all got cross posted into a specific forum for all to read. For users who weren't trying to offend this served the same lesson the Paper here makes: how to not do it again, for everyone else it served as entertainment while the mods hammered down trolls.
A case in point, I recently opened a bank account and needed to verify my identity by taking photo of my id and my face. I did it at least five times and always got just generic answer that the verification was unsuccessful. I thought that problem was with bad quality of camera or difference between my appearance on id and the taken photo and only later I realised that the id has already expired. Why didn't it tell me first time so I could use passport, instead of letting me try it over and over again?
With so much content moderation these days coming from machine learning (violates #1), personal vendettas from human moderators (violates #1 and #2) and quasi-legal threats from third parties (violates #1 and #2), there's not much room for user education left.
Those would also correlate "telling why content was removed" with "reduced future issues". But the causality goes the other way. Users that are likely to participate better in the future are more likely to get explanations, while spammers get nothing.
This is a good policy, thank you for doing it this way.
Personally I feel that something along the lines of an explanation should also go with downvotes. When I'm downvoted, I would like some feedback on what people didn't like about my post -- do they think I was rude? or did I write something that is wrong, or at least, would need a source to back it up? Similarly, I would also like to give such feedback when I downvote. But downvoting and posting about it is not welcomed by the community.
On Slashdot there is (was?) a rough category to go along with votes, so you could upvote something because it's "informative" or "funny", and downvote because it's "flamebait" or... I don't remember the others. Something like this would make a very useful addition to HN, I feel. The feedback could of course be optional, and only visible to the poster, like the actual score on a post.
The main purpose of the voting mechanism is to sort the responses within a thread, so that someone can skim a large comment section by reading only the first comments at each level of nesting. If it's working right, it should include the most interesting/relevant/accurate comments.
Tom_mellior, I can't quickly find any heavily downvoted comments of yours. One that's slightly downvoted is https://news.ycombinator.com/item?id=21417799, which is kind of low-effort. A downvote reasonably reflects the fact that it doesn't belong near the top of any list of the most interesting/relevant/accurate comments on the subject matter of the paper that a busy reader shouldn't miss if they're skimming quickly.
Most of your comments are great, so thanks for your contribution!
Yes. But often it's not clear, and would be useful to know, whether it's the "interesting" or the "relevant" or the "accurate" part that was lacking. These are all along the lines of the categories that I mentioned. I do want to stress that I did not propose a "you are a worthless human being" category.
> Tom_mellior, I can't quickly find any heavily downvoted comments of yours.
It doesn't have to be heavy for the reason to be interesting. And for whatever it's worth, there is this one: https://news.ycombinator.com/item?id=21362694 where I was downvoted for explaining why I downvoted someone. This is OK, since the HN guidelines discourage discussions about voting. Still, I think some sort of "-1, ad hominem" feedback would have been useful for the original poster.
In most cases it looks like dang does give them a reason when they’re banned but I don’t think many of them read it.
Much more common is banned accounts that post a mixture of good comments and ones that break the site guidelines. Those, unfortunately, we can't unban, for the obvious reason that the bad comments do more harm than the good ones add value. That's why we introduced vouching: so the good comments can still make it through.
Sometimes we unban accounts and as soon as they're unbanned they revert to breaking the site guidelines. Then we ban them again and they start posting good comments again. The human heart has murky depths.
We can see whether someone else's comment has been killed whether we're logged in or out, so maybe I'm not following your question...
But please don’t think I’m stuck on one side, there are good counterpoints that are similar to those about disclosing security vulnerabilities.
There are definitely different effects to the crowd and to the individual depending on the approach.
Isn't the problem the binary consequence, complete removal or completely left alone?
Instead, a continuous incentive gradient can push people away from the line. For example, comments on HN and Ars Technica that are downvoted are displayed grayed-out so they're harder to read and more likely to be skipped over when skimming; on Ars Technica, if a comment is sufficiently downvoted, its contents are collapsed into a stub, and you have to click the expand button to read it.
Besides pushing people away from the line, another advantage of a continuous incentive gradient instead of a discrete punishment is that because the stakes are lower, subjective disagreements are less divisive. If a comment straddles the line of violating the rules, and what's at stake is whether the comment is removed or shown, then community members will argue much more vehemently with each other and with mods than if what's at stake is whether the comment should be more or less gray, or whether the comment should be completely removed or merely collapsed.
(Zuck has discussed similar ideas about "borderline content": https://www.facebook.com/notes/mark-zuckerberg/a-blueprint-f... )
Or some way to collect moderation log data for reddit?
It costs nothing to start a new subreddit if you want different rules. And if lots of Redditors agree with you, they’ll happily follow you.
Regardless, it's still frustrating. Especially when they cannot tell you which "rule" you broke, so they resort to telling you they can use their discretion to ban you for any reason (which is usually some sort of agenda that becomes apparent after you've tried to have a civil discussion about why you were banned). It's what drove me away from that platform, and I'm sure I'm not the only one, so I guess not telling users also prevents future issues, in a way.
Sometimes you just have to show boorish guests the door.
Let it run on a set of rules, and count votes to change rules. Now you have DemocracyBot
(Just like every other group: self-serving.)
One of the weaknesses of this is how, at least on some subs, mods are able to censor discussion largely unnoticed, without being held accountable to the community. See r/declineintocensorship, r/watchredditdie, and r/yallcantbehave for several examples of egotistical mods overextending their role with no real benefit to the community.
I can't help but think that there's a way to hold mods more accountable to their communities. For example, if the modded comment wasn't spam, it could say "this post was removed for breaking rule x which states y. Click here to see the comment," with the mod's username attached.
I would also like to see statistics on removed posts, where a subreddit gets some sort of penalty for censoring too much, such as not appearing on /r/all, or becoming downweighted in some way.
Which certainly doesn't violate any laws.
The unintended consequence, however, is more isolation and less engagement with ideas you don't already subscribe to or people you don't normally encounter.
This is not a Reddit specific problem of course, it applies to Twitter and Facebook or any other social media platform. But it's concerning and difficult to find any easy and obvious solutions.
> WHY IS THE LANGUAGE SO NEGATIVE/PUNITIVE? THIS'LL TAKE THE FUN/CASUAL ATMOSPHERE OUT OF MY EVENT. THE PEOPLE ATTENDING ARE MY FRIENDS, I'LL VOUCH FOR THEM. ISN'T IT OBVIOUS/COMMON SENSE WHAT'S ACCEPTABLE? WE'RE ALL ADULTS HERE, WHY CAN'T WE SAY "BE EXCELLENT TO EACH OTHER"?
Not everyone understands what is unacceptable behavior, especially when we are talking about a group of people that is mostly homogenous and has very little interaction with people different than they are.
We focus specifically on what isn't allowed and what violating those rules would mean so there is no gray area, no guessing, no pushing boundaries to see what will happen. "Be nice" or "Be an adult" doesn't inform well enough about what is expected if one attendee's idea of niceness or professionalism are vastly different than another's. On top of that, "be excellent to each other" has a poor track record [link, now broken, previously described a real-world situation where people holding grudges tried to weaponize a community's sole "be excellent" rule against each other].
You may have been running an event for a long time and many of the attendees feel they are "like family", but it actually makes the idea of an incident happening at the event even scarier. If someone is new and not part of "the family" will they be believed? Will they be treated like an invading outsider?
Remember that everyone who has harassed or assaulted someone is a parent, sibling, child, or friend to someone else. We don't always know people as well as we think we do.
I mean, if you go to a restaurant, a movie theatre, or a supermarket, do you know how NOT to be an asshole? It's not hard. Most people can manage it on a day-to-day basis.
I don't know where you're veering off to in your last sentence either. Weird.
Of course most people can manage not to be an asshole on a day-to-day basis, but to deal with the small minority of bad apples who could ruin a whole barrel, it helps to spell out specific banned behavior in detail to quickly shut down arguments about whether a specific behavior is being an asshole or not.
The last sentence is pointing out that just because you've only ever seen someone be a nice person, doesn't mean they've never been an asshole when you weren't there.
Also, I didn't write that sentence. Everything after the first sentence is quoted from the link I provided.