I’ve won games no healer vs. healer, and lost the vice versa. It’s tricky, but if it’s like, a Tyrande that can’t attack very often vs. an Azmodan, I’ll pick the Azmo because the value from that top tier is way higher than very low heals.
However, that cannot be stated for frontliners. If the enemy team has, say, a Diablo or even a Mal’Ganis and the best frontline/peel you have is a Rexxar, you are doomed to a loss. Being able to say, soak Li-Ming Orbs, or stun reckless dive from the other team is essential to actually sway the win from one side to the other.