When you look at it like this how is Warrior a worse tank?

[Kaalan]

Overall a WAR does do more DMG than a PLD. Since threat is based off dmg this allows more time between hate building combos to pop abilities that self heal instead such as IB.

They deal roughly the same amount of damage and while PLD just spam an high threat combo, warrior has to alternat with a really low hate combo, so no. WAR, at best, deal the same or like 5% damage than a PLD, but with equal gear and "skill" (not like it takes any) a PLD have more threat.