People often post quick answers as comments. This completely makes sense if you're not sure whether you're correct or if you don't have the time to make a complete answer.
However, I've noticed that sometimes a good answer in a comment can discourage people from posting an answer. No one really wants to "steal" the answer from the commenter. Here's an example that I ran into while browsing the unanswered questions list:
What's the right way to deal with such situations? Do we just hope that someone will eventually write a more complete answer, or is it just overkill to worry about it at all?