If your goal is to post problems and associated solutions, yes it is better than a Wiki.
First, it gives you a template to post in - you are not given a blank page and told "document this"
Second, it encourages you to document single, smaller, focused pieces of information. You're not being asked or expected to write a multipage document, you're being asked to write a single entry in what essentially is a crowd sourced FAQ.
One thing the SO approach also does is that it respects the content that each person posts. If I post an answer, only I can modify it. Nobody will modify my answer to reflect what they think, and make it seem as if I was presenting a different solution that what I suggested. What people with alternative ideas CAN do though is post alternative answers, or comment on my answer with suggested changes.