I don't think this will happen. And if it does, it won't be a common occurrence. I'm on PS4 and have been on different servers and never seen a group exclude Playstation players. They're there, yes, but in small numbers. I believe the same will be true of those who use add-ons. A very large percentage of FFXIV's community is on PS3 or PS4 and wouldn't be able to run them. You'd quickly find that recruiting players that meet such a specific requirement would be so exclusionary that it might not benefit you at all, especially in situations where you lack a healer or tank for a static run. That's a comparatively small pool of people to pick from as it is. Requiring that they be on PC and have a specific add-on would only make it smaller.