Originally Posted by
Teriz
The chronology of WoW isn't the point. The point is that a Demon Hunter is only going to be hunting demons. They aren't going to be joining adventurers on quests that don't help their goal- Killing more demons. Mists of Pandaria for example had nothing to do with demons. Why would a Demon Hunter be a participant in those raids? The very purpose behind the concept doesn't work for WoW classes.
Then there's the problem of weaponry, armor, racials, name, abilities in other classes, etc.
Shaman are casters. They still have a melee spec. If Shaman can do it, Warlocks can too.