Originally Posted by Kasi

It's because those two classes are melee. They need to stun and hamstring to keep physical range so they can do something at all. Look at how Enhancement Shamans who are similarily powerful in melee and are arguably better against casters do so badly because Frost Shock is not as powerful for maintaining physical distance, and once they lose range they have no way to get it back.

Amongst ranged dps classes (mages, locks, ele shamans, boomkins, shadow priests, hunters) Warlocks are unique in being able to deal dps to a target they are CC'ing. Hunters and mages can Frost nova and scatter shot, but those break upon damage. But still why does that matter much? Even without fear a warlock can solo any class.