If I recall correctly certain classes had different dispels as well. Meaning a Ret could dispel magical effects like Fear/Poly off targets just like an Hpally, but neither could dispel poisons.
Not all healers can dispel the same types of CC and debuffs which is why certain healers were used in certain comps. It’s not the same as the “remove all” 8 second cooldown crap we have right now.