There's a thread on the Healer subforum where I suggested adding a "disable help from allies" feature similar to other games like Dota 2 where a skill can be used to either save a player or potentially troll and kill them. It seems like a good compromise to protect people from griefing and purposeful killing if they're worried about it, protect them from unwanted use if they care about it or are trying to greed with manaward or something similar, but it would still keep the skill around for the people who do want to use it and want it used on them for strategies or otherwise.
Nothing really outside of Extreme, Savage, and Ultimate really punishes a player for failing a mechanic past just killing them individually, so the risk of a player not being rescued and causing a wipe is pretty slim. It also pre-empts a lot of arguments about it by letting people decide if they want to be pulled or not.