I haven't left, I just cut back a lot. But I have contacted several who have posted "goodbye" threads and they just seem to be ready to move on with their lives. Which is wonderful. Leaving sites like JWD is part of the healing process.
I don't really take it as needing this board...I just like it. As Kida wrote above, it is always in flux and there is so much to visit about. When I really get struck by a topic or see someone in need of talking to, I put a bit more importance on that subject, but I don't think this is something I have to outgrow. Do you outgrow helping people or does anything really need clarification as to when it starts and when it should end on a discussion board? Maybe I did not need it to recover, but I have met people who helped in ways I did not know I needed it.
So with that said, I think I will just keep hanging out a bit. Somedays I can give more and others you wont see me for long stretches. It is just something I do and enjoy.