can be gear but also i would say how good the tank is.
I have already got agro from tanks that had better gear then I, and yes i let them build agro and yes i use Quelling Strikes.
Ct is actually very bad for this now. Granted perhaps tanks that go there are perhaps not geared that great but agro is for sure issues.
As for Brayflox HM, yeah we do big pulls and i do triple flares but never has been a major issue there