I've posted enough links in this thread. Search for yourself. If you don't want the RPG books to be canon or want to twist semantics, be my guest I don't care.
@Warlock popularity: I think it's quite obvious that I was talking about the theme of the class and not the actual gameplay / mechanics. Being a bad guy that summons demons appeals to many little kids that are tired of being the good guy. No offense towards the warlock community intended, i am speaking from a business PoV.
@MickM Sure you can justify everything somehow. But that doesn't mean it's a good thing when heaps of Draenei locks start running around. Because from a RP PoV, Individuals like my priestess or your lock would be a _very_ rare exception.