I don't believe that this answer is of any use on the site:
I disagree. What you're talking about are pat answers. They're short, direct, to-the-point, usually quite correct. But incomplete. They impart knowledge (do X, don't do Y, etc), but they don't provide wisdom (why should I do X, why shouldn't I do Y).
Some people need pat answers. Some people aren't ready to know the truth. Some people aren't ready to know everything about everything. A simple shove down the proper path, feeding on the accumulated knowledge of others, is sufficient to their needs.
Take this as an example. I know nothing about password security; I do entirely different kinds of programming. Seeing this question answered with a header-sized NO, coupled with lots of upvoting, is enough to tell me that it's probably not a good idea. I don't need a 30 paragraph dissertation that ritualistically vivisects every argument for restricting passwords. I just need to know if I should.
Now, that doesn't mean I think the dissertation shouldn't exist. But the fact is that some people don't need or want it.
That being said, the answer itself isn't the problem, is it? If it were a bad answer, it would be downvoted and that would be that. The problem is that the voting system is promoting the pat answer.
I believe that this comes from one simple fact: what does it mean to upvote something?
A lot of forums, YouTube, etc, have voting systems for comments. Thumbs up for "liked it!", thumbs down for "hated it!". Democracy only works when everyone is saying the same thing with a vote.
I guarantee you that most of those who voted for it were thinking, "Yes, he's right." They weren't taking a considered and reasoned stand on how useful his answer was in a broad sense. They saw the answer, agreed with it, maybe chucked at the bluntness of it, and voted it up. Because they liked it and it was correct.
That's how voting works. Not everyone thinks that their vote means "this was a reply that will be a font of thoughtful and insightful knowledge for any passersby." They simply thought, "he's right, and that's funny."
So until you can find a way to make everyone use their vote to mean "thoughtful and considered" rather than "correct and liked it," then this will continue to happen.