Here is the thing let us say the healer used it to force larger pulls the only way a wipe would happen is if the tank does not grab aggro which with the new tanking changes I cannot think of many legitimate reasons for a tank to not be able to get aggro short from mentioning they were AFK or something. So I would say the wipe was on the fault of the tank, now if the healer was overestimating their own skills and the tank got aggro, used cooldowns etc . . . that is a different story.
I guess a better way of saying what I am trying to say is even if the healer forces a larger pull if the party wipes due to the tank not getting aggro or using cool downs, the tank is also responsible for the wipe. Sure the healer put the tank in the situation where a wipe could happen, but if the tank froze up and forgot to push buttons, then their actions also contributed to the final outcome IE the wipe.