When I see a tank not using their cooldowns I just think this is going to be a run with a ton of healing. But I won't stop healing a tank just because they aren't using cooldowns.

I probably won't even say anything (unless it is a low level dungeon) because I'm sure the tank knows exactly what they are doing.

Unless people start dying, I'll just heal the best I can and get everyone through the dungeon safely.

However, if it's a DPS who continues to pull mobs before the tank, I will tell them to stop. If they don't, then I will stop healing and reviving the DPS who wants to pretend to be a tank. That really grinds my gears.