Ok this is ridicolous. As a tank I don't panic in expert dungeons until I'm like 10% HP or less, and even then if I die it's the healer's fault, why waste so much dps on an heal? In any case a res takes a moment and gets you back up quickly.
As a healer keeping people topped is overhealing and also the least you dps the longer it will take for the pull to die and the more in trouble will both the healer and tank start being. Ironically, it's SAFER to heal wisely and in a planned way and make stuff die faster with dpsing (plus the stun if whm) than to just spam heals for a long time.

As for RDM, that's a whole different matter, as using one Vercure isn't much of a dps loss.