Not sure I agree with you there dude. Sure a healer can help turn the tide but if the people he's healing don't know how to deal damage then it's not going to matter how good a healer he is. Same goes for any class if the best damage dude in the world doesn't get heals then as soon as he starts to get focused he's not going to last long either. Sure both the healer and damage dude in that scenario will get good scores no doubt but doesn't mean to say they'll win.
The whole thing about being able to carry a team is extremely subjective. It depends on a number of factors, if the other people in the warzone (allies and enemies) aren't up to scratch then it'll be far easier for the sorc, jugga, mara, sniper (basically any class) it'll be to effect the outcome.
really all classes supposrt each other