I think it's just easier to recognize elitists, the people making unreasonable demands so you'll be allowed to join the group. Of course there's a flip side to that, people can make unreasonable demands on the opposite side of elitism, if that makes sense. Like expecting a free ride through a dungeon or asking random people for money in map chat. Not saying the lvl 20ish person expected a free ride, but hell, he could've been anyone. Guess I wasn't willing to take that risk of wasting my time.
You would have to define unreasonable though. For someone to join an UW group in GW1, they would have to show like 200 Ghastly Stones. Is that unreasonable for someone new to UW? Yes. Is it unreasonable to a lot of players? No. Many people have several times that amount.
The other day I formed a TA run, and three pugs came along. They were guardian / mesmers and we asked them to bring Wall of Reflection and Feedback for Malrona. To them this seemed like a totally unreasonable request. Needless to say we shut down that instance as soon as we realized, because adapting a build as we go along is the very minimum of what we expect from players in a run.
My point is, some people will always have a much lower bar for what is reasonable, and will call anyone enforcing anything above that an elitist, while these so called "elitists" are only doing what's in their best interest.