Play EH or higher. Warlocks don't scale well past ENI've played warlock and it takes next to nothing other than a few common sense decisions to make them far more overpowered than you can do with anything else. And if someone knows what they are doing it goes from being ridiculously overpowered to stupendously, ridiculously overpowered. Yeah, you can mess them up but you almost have to be trying to mess them up.
I made a pally/warlock, walked around with my aura running and not blasting anything and was still getting complaints about killing everything.I've seen some first lifers gunk up a warlock. But far and away most just put everyone to shame. It absolutely makes the game not worth playing unless you are playing warlock. If you get in a party with a decently built one and you may as well just pike.
And why? Why do you want to just kill everything instantly. It's like some five year old's idea of fun. Design a game where you walk in a room and everyting dies. Weeeeeeee. I'm winning. Why don't they just make it so warlock blasts just kill the entire dungeon so we can walk around and pick up the loot. That is essentially what most of us non warlocks end up doing anyway.
And it really is indefensible. If you think in your screwed up logic that it isn't a problem, you just have not been playing this game. Look around at the number of warlocks being played. Look at the LFMS and all the high reaper levels, almost all have 2 or 3 warlocks. Look at the number of kills they almost always have compared to anyone else. Yeah occasionally someone will kill more, but not often. Probably just when the Warlock started feeling bad and quits really trying.