Khajin the Unyielding in HOI had a major heal check. I’m not talking about just this season, but M+ in general. Heal/DPS checks exist that can be a brick wall for the non-tanks.
My guy, you can perform flawlessly as a tank and still have keys where the other two roles screw up beyond belief and brick the key. That’s the nature of M+. The key does not revolve fully around a single role or player.