I think the worst aspect is the endless "your premise is flawed, you should do <this> instead" answers. I often formulate toy examples, or ask questions out of curiosity rather than practical need. Somehow, users always latch on to the irrelevant part of my question instead of answering the part I care about. It's gotten to the point where I put big disclaimers in my questions to steer users away from those useless (to me) responses.
I got so annoyed with this pattern that I now consciously avoid writing anything that's not a direct answer to the user's question. I wish others would do the same.
Sometimes I will write a very broad answer, especially when it's apparent the person doesn't seem to have looked into finding anything, and just asked a question on SO, which happens a lot.
The problem is that not everyone is a very good teacher or judge of when it's proper to give advice. So you get a lot of people who don't know the answer and instead provide some workaround using technologies they do know and are comfortable with, which isn't necessarily helpful.
In text-based communication, deciding what is important is 100% on the reader - and while to you someone may be responding to irrelevant parts of your questions - to them, it is what they found interesting and thus important.
In face to face communication, the onus of importance is far more shifted to the speaker, because based on tone and facial expression - combined with societal norms - the listener has a much easier time seeing what you find important and a much harder time being able to only latch on to the irrelevant tidbits.
> where I put big disclaimers in my questions to steer users away from those useless (to me) responses.
I have found myself doing a very similar thing - essentially trying to convey the information that gets lost of text to insure the reader can understand what I want to convey is important.
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