Secondly you are right that online discussion fora can become an insane time sink. Certainly if you spend all of your time at work helping others you are not, on the whole, benefitting.

That said it is the rare person who can learn effectively without outside input. If you are incredibly lucky you will have that kind of input locally available to you. Most of us have to go elsewhere to get exposure to people, technical points, and ways of thinking that cause us to grow.

So I would suggest whittling down. Decide how much time you feel comfortable spending online. Then decide where you want to spend it. Personally it is a major form of entertainment for me..from home. I sign in from work, but I limit how much time I spend online. (What that limit is depends on what is going on at work.)

And if you are the kind of person who gets into flamewars and then is left upset and frustrated, well I definitely recommend avoiding places where you get into flames...