Only because everyone cries for nerfs any time they prove to be useful. Whether it be for defense, offense, or even healing others in the case of Prot Pally. It doesn’t matter if they get nuked by the same 3 specs all expansion long, but the first time someone loses to a tank they lose their minds and Blizz comes out swinging with the nerf bat.
They should remove CC from everyone and only give CC to tank.
Tanks shouldnt even be in PvP and if they are they should have a similar kill time to there counter parts minus the buff and debuffs they can apply. Ill never forgive blood DK’s for there past in PvP 
*their