Because in the tooltip in nowhere does it say “Take this class for PvP only” instead it says support. In the great scheme of things a hunter is not enough to win. Sure you render a single target without doing anything, watchout there’s another 4 out there.
In 2 v 2 it renders 50% of the other team useless, but guess what. that doesn’t mean that other person is not a threat. Killing with a hunter alone takes an eternity. if you say “oh they kill fast” no hunter doesn’t kill fast.