Originally Posted by
Shurrikhan
Roles" are, in the end, mere specializations for which a degree of primary capabilities (damage-dealing in the case of any fight cleared by killing the enemies, or healing in any fight cleared by topping off a given NPC, etc.) is sacrificed to allow a higher degree of capacity for handling secondary functions (anything tactic that improves your raid's ability to clear the encounter that is not a direct, or primary, capacity, such as by reducing the ratio of incoming to outgoing damage) or tertiary functions (anything that improves upon those secondary functions while not directly contributing to them).
This.