I think that most people who are confrontational and critical online are just like that in person. People can be quite blunt face-to-face, and are perfectly OK with it when people are blunt to them. Blunt interaction has the big advantage that you never have to second guess what a remark means. Consider how many relations (between friends/colleagues/etc) break up because somebody reads too much in a simple remark. The most tactful people also tend to be those who (needlessly) worry the most about what other people say. I say this just from personal experience, so YMMV - but it's worth considering.
As for the Mr. Spock argument, I think that has a much more mundane explanation. I, like most people, read far more on the internet than I write. But when I read I read to learn. Therefore, I want to be reasonably sure what I read is correct. Because of the Mr. Spocks amongst us I can read the comments and use that to figure out if the blogger made any sense. More often than not the comments reveal serious flaws in the blogger's post. It is this interaction between blogger and Spocks that leads to better understanding. Both for visitors like me and the blogger.
So the Spocks fight against the pollution of the internet by incorrect statements%. It's a futile fight, but I believe it's a noble one. Frankly, I think posting uninformed and wrong comments is far more inconsiderate than pointing out to all future readers that such a comment is uninformed or wrong.
%) You called it an internet maxim in another post.
I had a customer once that wanted me to hire a team of the best consultants we could find.
So I spent about a month reviewing resumes and doing interviews. At the end, we had about 8-10 folks who had top-drawer experiences, top-drawer credentials, and top-drawer recommendations. (Their rates were top-drawer too, but that's a different post)
Once they started, I found that I was wrong all of the time. If I said it was raining, one person would say nope, it's misting, another would say that a better term would be scattered showers, while a third person would point out that the technical meteorological term was BR.
It went on like this for weeks. Whatever my opinion, technical or not, was wrong. Drove me nuts.
Then I realized that these really sharp folks were simply acting the way they had their entire careers. People who criticize and correct get noticed as being smart. You can either be a wallflower or you can stand up and show how much you know.
These were great guys, but they weren't working as a team. Instead, each was jockeying to look good.
Not sure if my example directly applies, but it at least seems to me that a lot of folks are simply playing for points, ie, looking to nitpick instead of trying to learn.
People are tough, you know? Computers are a lot easier.
I've been in the situation you've described (and I've been part of the problem). And yes, it can be really frustrating. Some teams don't work. And sometimes a single person makes or breaks a team. This is fascinating by itself, but a bit off topic.
The big difference is that online the reader to writer ratio is way different. Online, when somebody points out that a hash-map insert is amortized O(1) instead of O(1) hundreds or thousands of people benefit.
When the contractor tries to convince you that a scattered shower is different from a heavy mist (even though you're not in the least interested) nobody benefits. It's just noise.
As for the Mr. Spock argument, I think that has a much more mundane explanation. I, like most people, read far more on the internet than I write. But when I read I read to learn. Therefore, I want to be reasonably sure what I read is correct. Because of the Mr. Spocks amongst us I can read the comments and use that to figure out if the blogger made any sense. More often than not the comments reveal serious flaws in the blogger's post. It is this interaction between blogger and Spocks that leads to better understanding. Both for visitors like me and the blogger.
So the Spocks fight against the pollution of the internet by incorrect statements%. It's a futile fight, but I believe it's a noble one. Frankly, I think posting uninformed and wrong comments is far more inconsiderate than pointing out to all future readers that such a comment is uninformed or wrong.
%) You called it an internet maxim in another post.