I'm not sure I'd call it elitist. Sessions have an etiquette and many sessions encompass established social relationships. I have felt excluded at a session, to be sure, but no more so than when I go into a bar where I don't know a lot of people, and everyone else is a "regular." The solution is to keep going to the session, and keep practicing the tunes you learn there, until you're known and "up to speed."

I guess the question is, is any form of interaction that has rules by which people are supposed to abide elitist? Would we call, for example, a conversation elitist if the speakers resented a stranger who couldn't speak the language but kept interjecting things anyway? If not, then at what point does session etiquette become elitist and at what point is it merely a set of unspoken rules of communication?