Most posts made by people never get replies or followed up or discussed. So I guess that tends to kill interest in posting.

The PGD games competition gets people involved.

I think quite a large number of visitors only visit looking for an answer to their own particular problem.

I found with Omega and in a smaller scale with DJX that people working with same components and sharing code and stuff makes for lively and interactive forums. The PGD games competition had a similar effect here.