Before I ever went on a forum, I never read, had a poor vocabulary and my understanding of general concepts was lacking.
I'm naturally a smart person, but I never put the work in at school and college, and that remains my number one regret. However, I found that public forums gave me licence to debate, give and receive advice, and to discover new hobbies (Reading and programming).
I've learnt a lot personally and I owe most of it to public forums because without it, I would have never discovered my favorite book which got me into reading, and the help needed to pass my Computing A-Level (although I could have stayed behind for catch up lessons, but my teacher was a dick).