I'd wager it's more a case of people not knowing how to play their class. I've healed through big pulls plenty fine as long as the tank's using mitigation. Doesn't even need to be overgeared.

MAYBE things have more HP and hit harder, I dunno. I do know that for trials I hardly even have to get healed, but they take sooo long because people are dying 4-5 times each. There's some times where you've got to use AoE heals because of multiple stackers but it's not that big of a difference.