Dont feel like a Tank in PvP

Im not a very high rated play by any means, im usually around 15-1600 in RBGs.
Ive been playing Prot warrior (yes i know, “Just reroll bear”), but that not my problem.
My problem is i really dont feel like a tank when a Rogue destroys me in a 6-8s Stun Lock.
I know tanks take 50% more dmg in pvp content. But Why? Why increase my Dmg taken and not increase dmg dealt?
Why do i die in 6-8s as a Tank? Yes a Prot Warrior, none the less a Tank.
Yes i have seen Bears get absolutely owned by a rogue.
I dont want to hear its the Master Assa Leggo, or their build.
I trinket the stun, Zerk Rage the Sap. Still get stunned and smoked.
I want to know why its ok to be able to dust someone from 134k hp to 0 in 8s?