On this topic, I find that some old questions have incorrect answers. I try to leave a comment on those questions. Most of the time this seems ignored.
To be honest with you, who made me the authority for determining what is the "correct" way to write a singleton pattern for c#? I did my best and chose the best answer at the time. Stuff changes and a new "more correct" answer may pop up. Just because I asked an question first, does not make me the authority for "the answer", in SO it does.
I think that after a certain amount of time, questions should become community owned. And "the answer" should become community owned (by rolling up all of the data into a single answer)
Perhaps we should allow for duplicate questions, if the new one is more concise with rolled up answers (from possibly multiple questions) - referencing the original.
Perhaps the answer is just to comment-and-wait.
Perhaps we need a meta-moderation scheme.
Perhaps we should allow people to vote that a question is not really answered.