What kind of squishy tanks have you been running with, that die in one GCD to 3 mobs without cooldowns? *blinks* That's some serious fail there. I just ran Ala Mihgo earlier, and I'm wearing the stuff you get from the Lv70 PLD quest, with 2 Omega accessories and the rest is Verity. Hardly the best geared tank around. I was doing 5-6 mobs at once with no cooldowns (I only pop those if I see the healer is struggling, or if it is an actual big pull or something dangerous actually in that pull).
But then I'm a bit more quick to reach for the Clemency button even if the healer is healing me because I know it makes their life a lot easier and I usually have MP to spare, and I like to help them.
Really, though, I cannot imagine a tank dying in one GCD to 3 mobs. Does this really happen? I've never seen it, even when I run as WHM. I've never seen this, ever. The closest was actually today, a tank in Amdapor who decided to pull FOUR GROUPS AT ONCE who had to pop Hallowed Ground just to give me enough time to land two Cure2s to save their life. Well, they botched the pull right after the first boss; they were pulling so ridiculously many mobs that they were using potions on cooldown just to stay alive. Well, she went JUST too far and she wound up dropping dead in the middle of a Cure2 cast. I assume her Hallowed Ground was down and she was expecting it to be up, or her potion was on cooldown or something, dunno. But she was dead before I could even cast. lol.
This is the kind of mentality I hate with a passion. There is no reason to be in such a hurry. The "precious" few seconds the tank would have saved by pulling 4 groups at once were lost several times over in the time it took us all to rez and run back for another try at that pull. We killed exactly zero mobs in the whole fiasco and it set us back 3 minutes+. If she had just stopped one group short, we would have saved a lot more time.
While I do not agree with or condone the "HEALER MAX DPS!!!!" Mentality, I will have to admit that at least as a WHM, Stone IVs hurt. They hit surprisingly hard, and Aero III is actually a decent AoE. Holy can sting a bit, and if you get 6+ mobs, you deal a rather large chunk of damage and it even AoE stuns to boot.
But... finding time to cast it... not so easy if there's that many mobs.
Again, WHM can put out a decent amount of damage, but damage is always secondary to the main reason they are there, and if someone dies for lack of heals, then it is the healer's fault, period. Yes, maybe a tank decides to pull too much and fail to use cooldowns, but if he drops dead while the healer was DPSing, the healer is the one in the wrong.