I'm one...and though I'm relatively young (under 22), I don't think that my posts there are too bad. Of course I don't know too much about technical stuff, but sometimes I'm amazed at some of the stuff that's posted there...as nwelite has pointed out, there are a few people my age but such silly posts as the A vs B war, AN/QF war (which I have to say takes place on FT - maybe it's just us Aussies), best airline etc., they're not particularly enriching. Occasionally some of the topics are interesting but they're few and far between.
I don't pretend to know a great amount, but I have to defend myself as reasonably knowledgeable, therefore I tend to comment only on posts I do know something about.
Or picking flaws in ignorant posters' arguments
Regards,
Clement