It's not an exploit, it's people realizing certain classes are significantly more capable than others in PvP. And an only healers party is a very slow burner as far as DPS is concerned, only good for defense. 3-4 healers is plenty to weather just about any storm. So the real question is balance. Things that work fine for PvE aren't necessarily scaled well for PvP, so perhaps some curative balance is in order. Either way, just like fighting games, there is a very clear and established tier list, and balance can definitely be better. We'll see. I'm enjoying Scholar being insanely powerful in utility at the moment.