I've responded to this question (the link is for 10k users; the cached version before removal is here), and put quite some effort into my answer that received 2 votes. I wanted to look at it again and, saw that the question was deleted, from my answers list, from my activity and reputation history.
Everything was deleted in such a short time!
You might argue that the question was put wrong, but I tried to handle it in the answer, and I tried to lead the OP. And the question with all answers was deleted without any discussion. This means I wasted my time completely and it won't help anyone.
I don't think this is a good way to motivate people to answer questions on Stak Overflow.
Update after Jeff's answer: I found the question quite straightforward and complete enough to formulate my answer and lead the OP. And I think it could help the OP. If this is not the purpose of the site, just correct me. I think the responder is the one to define whether the question was specific enough or not. (Moreover, there were similar questions like this one in the past, so I think it is useful also for others, and not too localized.)