I found wikipedia's interface to be pretty unfriendly for me as a new user. Stackoverflow was a lot easier for me to get started with. Maybe that lower barrier to entry leads to more random posts from people that are "low quality?"
Side note: I find a similarity between SO and HN. Both can feel pretty hostile and over-the-top with penalizing you for not saying things "the right way." But as much as it does annoy me sometimes, these are two of the most useful websites for my purposes.
Stack Overflow is worse because the questioners are approaching it in the vulnerable state of "not knowing". This makes the smack-downs worse, because the user already had a problem, and now they have haters as well.
Maybe worse for you. My experience certainly contradicts your claim. And I suspect that your claim is anecdotal as is mine. The difference is I am only speaking about my experience where you are attempting to make a sweeping judgement based on your experience.
Side note: I find a similarity between SO and HN. Both can feel pretty hostile and over-the-top with penalizing you for not saying things "the right way." But as much as it does annoy me sometimes, these are two of the most useful websites for my purposes.