And how do we ensure that only "professionals" get into the "Professionals" forum?
My personal view, which does not in any way necessarily represent the views of anyone else, alive or dead, is that PPRuNe benefits greatly from the views of all who are interested in aviation, and a very high proportion of those are not pilots, cabin crew, regular passengers, dispatchers, ATCOs, baggage handlers, journalists or even airline management.
The posters I find personally irritating come from all sectors, and they are the wind-up merchants - those who are only interested in stirring it, not in finding any enlightenment, assistance or in provoking thoughtful conversation, just in seeing how many they can annoy the hell out of.
Judging from how many hits the site gets daily, it works pretty well as it is.