Why Crit for tanks?

[Rithy255]

So why do the BiS websites have Crit materia for tanks? They don't outdamage any of the DPS, why wouldn't it be best to put in tenacity or determination?

Tank damage while it doesn't "out damage" DPS is still pretty strong, around 60-70% worth of a DPS values, Tank and Healer dps matter a lot towards a enrage, one tank and one healer together would even outdps one dps, so it's very important to damage on both roles.

Tenacity isn't picked because tanks already have more then enough mitigation to the point of having more is just useless, the damage gain is smaller then determination, which on det you don't use as much as Crit/Dh. So you almost never want tenacity, even if its mitigation benefits sound good on paper it's not.

Determination is a decent stat, but tanks would rather have Direct hit because they lack Direct hit without melds because tank gear doesn't have them built in, this stat might be better on DPS due to them having direct hit built into gear

Stat priority is Critical hit > Direct hit > Determination > Tenacity/Skill Speed. (sometimes skill speed is fine, though on jobs like PLD who use spells you 100% want to avoid it if you can).

Stat priority is just based on max damage, because in ff14 damage is the most important even on tanks and healers, crit is great because a burst critical hit attack does a lot of damage and crit scales better then any other stat.