StackOverflow is being killed by its overzealous moderation, as was Wikipedia a year or so ago before they backed off a bit. Let's sample a random question from the `php` tag: [1]. The question is not particularly well-asked, but I think it's fairly obvious that the answer is a union of the three tables. And yet, because he phrased his question as a requirement (it's the last sentence) and not an absolute question, it's been closed – even though I understand the question and possess the ability to give an answer (and maybe even edit the original question to improve its readability), I've been rendered unable to do so.
I think the big problem I have with quickly-closed questions is that they get just as thoroughly indexed on Google as answered questions. This becomes a particular problem with niche topics; last summer, I was tasked with some Salesforce development and the number of unanswered, closed APEX questions I found was astonishing.
[1] http://stackoverflow.com/questions/17237166/sql-query-query-...