I'm going to keep this short. His heal shouldn't be AoE. It heals a good amount and can be spammed, making him as a tank self-sufficient. Tanks always need backup.

QED

first off your argument was against it being an AoE, but then you also offer a reason that it's also wrong because it makes him self-sufficent and solo(??). these are two different things.

finally, wrong. it doesn't heal nearly enough nor fast enough to make him immortal or regen quick enough to leap from fight to fight without a breath, equiv to someone base to the fountain and teleporting back.

Wonder if OP has ever played "Immortal Heal Alistair" he seems to imply is viable.