Yeah, veterans that bail on trials because there are new people is just plain rude, but so are new people that go into these situations with no idea what they are doing. There are a ton of guides out there, and if you are going to go into endgame content or a trail marked as Extreme, then you should go in with some concept of what's going to happen instead of "I like to go in blind for fun, now explain every step to me before we start".