I think part of the answer is Facebook overall is easier to use with a phone and simple to add pictures and videos to a post. Facebook is also not as narrow, people belong to multiple groups and see what their friends are posting in one place.
As far as the reputation of the PGCA on Facebook, it could be there is more focus on the higher grade, unique and originality here that comes across as snobbish but who knows.
P.S. As far as rude, arrogant, snobby, old guys goes, they got the last part right
