"Muh DPS!"
Sadly, this statement is what FF XIV is built around, regardless of role. Tanks running in DPS stance, refusing to swap back to tank stance when the aggro table gets iffy. Claiming the DPS should use aggro deflection, then if the DPS do, they claim the DPS should hold back. Then the 101 flammable threads about healers that don't DPS. And, of course, you get DPS who, even if they see their tank is struggling, refuse to give up even a single point of DPS to help. The job of the tank is to DPS hard, oh, and maybe manage aggro. The job of a healer is to DPS hard, oh, and heal a little. The job of the DPS is to DPS balls to the wall no matter what. That's the current mindset, and parsers are a large reason why. It's not about efficiency, party symmetry, or heaven forbid having fun. It's about having that high number on the parser.
Now, don't get me wrong, the game itself definately carries some blame. Why are raiders so focused on DPS? Because raids have enrage timers and your raid group needs to wring every last drop of DPS out like a moist dishrag in the desert or you'll likely wipe. And the game allows tanks and healers to do too much damage. If it were a case where tanks and healers could contribute a little DPS here and there, people wouldn't focus on it as much. But currently in XIV tanks and healers can put out so much damage that there is a notable drop-off when they don't. We're not talking about shaving a minute or two off a dungeon, we're talking several. If a nervous peasant has a dagger, I'm not going to be as frustrated if he doesn't use it, but if that same peasant has a handgun, I'm going to get cranky if he isn't opening fire, even if I have an automatic rifle.
FFXIV's design is such that it encourages this DPS above all mentality. Couple that with parsers and it's easy to see why this game's playerbase as a whole has adopted a DPS > All Else mindset. Of course there are exceptions. As a healer, I prioritize healing and weave in DPS where I can. As a tank, I will do everything in my power to regain lost aggro, including swapping back into tank stance if needed and sacrificing DPS. As a DPS I will use all my emnity flushes and even ease up on the DPS if the tank is honestly struggling. But I know the prevalent mindset doesn't match mine. Sadly, FF XIV would require a core philosophical shift to address this issue. Tank and healer damage would have to be slashed to levels that make it a nice, small bonus, not a signifigant contribution to total instance damage...which would immediately cause wailing, screaming, torches and pitchforks. So, sadly, I expect the "Muh DPS!" mindset to continue for quite some time.