Have we all done all the interesting topics to death and have nothing interesting left to say to, or ask of, each other?
That's the question.
I suppose, if you are looking for quality postings (however that is defined) then you are looking for an intersection between several populations:
a) pilots who do some real flying;
b) pilots who like to write about it;
c) pilots who have the time to write about it;
d) pilots (incl. newbies) who have a question to ask
I know for a fact that most pilots who fly really high hours (200+/year) do not participate on any pilot forum. They have relatively normal busy lives. They have read some forums, waded through the drivel, and never touched them again. Some remain on aircraft type specific forums but TBH those suffer from the same problem of a small group of twats posting drivel.
The best way to deal with twats is to pointedly ignore them or, if they make a particularly misleading statement, ask for a reference.
What destroys a forum fastest is aggression and personal attacks. There is a lot less of this here now.