Audiogon is very, very segmented. and instead of being owned by a hifi dealer, or dogmatic reviewer, or a laid back community, it's a purely commercial entity without a particular hobby perspective. so it's an outlier in terms of how it works and how the forum is moderated. and there is no one perspective which is valid.
if we just observe the Audiogon forums, it's the wild, wild, west. there is a commercial aspect to it where certain types of posts which might be negative toward advertisers are quickly deleted. some dealers are quite aggressive there. and a strong cynical, sarcastic objectivist group somewhat pooh-poohing more high end gear. but then there are very serious hobbyists that have serious discussions about interesting things and music too. lots of very inexperienced newbies doing newbie things at all points of the price spectrum. lots of very basic type questions.
so in general, it is inclusive of all levels of high performance music reproduction commitment; so it covers audiophiles and non-audiophiles. objectivists and subjectivists. a melting pot.
as far as the listings and sales from Audiogon, it's just a slice of the market. lots of dealers use it. much more reality on US Audio Mart in terms of overall depth and action. Audiogon is just the tip of the sales iceberg.