From one tank to other tanks..STR Gear is not a thing anymore..Get used to it now!

[RyuujinZERO]

This isn't about emnity.

Vitality is not mitigation, vitality increases the pool of health into which healers can pour their healing, and from which damage is subtracted.

Obviously a tank's HP pool has to be sufficiently large to absorb the damage they're going to encounter in the dungeon, long enough for the healer to replace it. But once you have enough, having more doesn't help in any way - it doesn't even help the healer to do more DPS, because a larger HP pool just means they are postponing their heal spells, they will have to spend the same number of GCD cycles healing them later on as they would if they'd just spaced them out.

Tank heals scale of STR; this is especially true for DRK who's AD+DA combo and Grit+Souleater return HP based on damage dealt. This provides a form of active damage mitigation.. This HP returned, whether by a PLD self heal, or DRK's life steal attacks, is HP that the healer does not need to heal personally, and this means the healer has more time with which to DPS!

The fact that the tank is also doing extra DPS and generating more emnity is just icing on the cake.