The fundamental "imbalance" of the classes is actually what you are complaining. Monsters cast one shot mechanisms if you move an inch away from them. You either need to stick to them like a smiter or let minions do the face-tanking.
P.S: You can't kill some bosses in five or fifty minutes as a summoner necro. I am okay with it if other classes have the same issue but with smiter it takes me literally 50 seconds to kill the new boss from starting the game.