I'm a new return, I guess it's been months, but it still feels new, and I've definitely run into these people. At first every group was extremely welcoming but around the time I hit 40 I ran into the WoW mindset a few times. Someone actually wanted to know what I had slotted before doing Manticore. Another required team teleport. He had some unpleasant words when I asked him if he had it, which I interpreted as "no." I've been sticking to working on alts for a while now and that's solved a lot of that problem.
I get it though, it can be frustrating when you're playing a kinetic and every time you try to target through a melee player to heal them you discover their target is on the other side of the room, or when your tank skipped as much defence as they could in favour of attacks or the thermal corrupter is laughing about only having taken one skill from their support set so you'll have to heal the 3 rooms the group is somehow fighting in at the same time - not that any of that happened to me all in the same group at once, tonight. The point is, newbs will learn - if you're patient it's not a real problem, but elitists don't ever seem to change, and the bars they like to set are often ridiculous. If only they would extend their elitism to disdain for pubs and stick to their SGs for grouping.