I was a member of a small self-help group that practically disappeared in two years, because everyone was too busy doing their awesome projects, and didn't have time to post. That was when I realized that self-help groups that persist for too long are suspicious.

Okay, in theory, the members that solve their problems and leave could be gradually replaced by new members, so the group could exist for a long time. But in practice, it would be unlikely to have the members sufficiently balanced, so the evaporation of the most successful ones would increase the fraction of the ones who are unusuccessful for all kinds of reasons. Also, trying to grow a group is in tension with vetting the potential members.