"Art," by definition is a function of individual perception. You may get a consensus among a large group of individuals that somethinf is or is not art but you will never get absolute agreement. Even if you could get every human being on the planet to agree, it would still be only an opinion, a perception, not a fact. Art is not like a carbon atom that would persist, immutably even if all life in the universe were to suddenly cease to exist, it's a concept People may enjoy thinking of theiir opinions, their perceptions as facts, but that does not make it so. I think that Thip hit the nail on the head here. The question is not about art, but rather about artists and the need for the particular type of ego fulfillment that perceiving oneself as an artist brings. The more exclusive the membership, the greater the ego boost. In this case, the only way to maintain exclusivity is to subscribe to a definition of art that excludes as many people as possible. Sometimes, those who perhaps feel less secure, even in their own self definition, feel obligated to act as protectors of the true faith, aggresively attacking infidels. It's probably no coincidence that Hitler wasn't an Aryan.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken