I have to disagree. If you're judging healers SOLELY by their ability to survive in a 1v1 fight, then sure, they're a little OP. However, all PVP modes are team based objective games. Two or more opponents can make short work of a healer (damage from two DPS, or one DPS while a tank stunlocks them). Even if you're the only one attacking a healer, making them need to constantly heal themselves means they are NOT healing their teammates, allowing your own teammates to take them out. Back when spells were interrupted by any damage whatsoever, it basically meant only instant-cast spells were usable.