While it's hardly an exploit, healers are notorious for being unbalanced in MMO PvP. It's a really hard system to balance correctly - if one DPS = one healer, it negates healers, but if one healer = 2 DPS, it gets REALLY grating and difficult to play around them, especially because so few classes in FFXIV have an instant, low cooldown off-GCD interrupt.

Also, we're still in the denial stage. Healers will fight you tooth and nail that they aren't frustrating to play against.