See this question in meta itself to see a simple example:
Sure the comments answered it, but it could do with an actual answer in place to make it so that it is resolved and people who have the same question can find it easier. A really cool feature would be the ability to mark the comment as the answer maybe?
Or am I just barking up the wrong tree here and I should let sleeping dogs lie?
I think that's a bad example because the correct answer is, "close the question as off-topic" ;)
If there's a useful answer that someone has already submitted as a comment, that's a great opportunity for a low-rep user to gain some easy rep by writing up a complete answer with some supporting text and links.
So if this is happening a lot, the real problem is that there aren't enough ambitious new users.
