To your point: Today, many of the questions devs encounter are already covered, and covered pretty well on SO Q&A. This is obviously good for devs looking for solutions. But combined with the fact that most new questions - that haven't been asked before - are answered quickly,it's hard for users trying to get involved and contribute. That'll all change with Docs.
There will be tons of need for contributions, plus the system has more checks and peer support baked in, so it'll be easier to know your contribution will help, even if you're not sure it's complete, etc. We're really excited about how Docs will let more devs like you who want to pitch in be a part of it. I hope you'll give it a try.