As more of a generalization, MMO players treating these games as endgame is where the game begins can be perceived as an issue. If a given game's dev embraces this philosophy, then the leveling experience can, in turn, wind up being quite shallow. Socially, there's also the trickle down factor where people blankly assume that what does or doesn't work at endgame levels will or will not work prior. There's also a sect that refuses to party with first-timers to content as it might mean actually having to explain something or slowing their precious speed runs down by a couple minutes. Essentially, it's the toxic elements of elitist mentalities that can and do worsen these communities if left unchecked or even encouraged by game mechanics.
From my perspective of XIV, the first time up and a little bit after shouldn't be too much of an issue on non-legacy servers while people are still feeling things out. You'll still have the sheepish can't-think-for-themselves parroting some guide/video they saw on the net somewhere and treat is gospel, but there's honestly not much you can do to screen that in the PUG environment. And if SE embraces the philosophy that there should be no singular path to equal progression, then hopefully people won't have to tolerate working with grating personalities only looking out for themselves within the forced group sphere. Unfortunately, I still worry about how people will take to leveling their second+ jobs due to the first run of quests being exhausted. Things may prove more lenient than the beta did, but that's pretty much wait and see status for me.