Just letting you know what the actual definition. Hunters, locks, mages, and rogues are the pure classes. And back in the day they were the top dps cause Blizz believed that being able to do something besides dps meant you shouldn't be able to dps as well as people who have that as their only option. Warrior being the exception because they were the "chosen" tank. Ret pallies and boomkins for instance went oom incredibly quickly (boomkins actually had a talent to regain mana through melee'ing), resto druids were kept purely to innervate the real healers (priests), paladins were buffbots without even a taunt. Vanilla was a weird time.
While writing this Stormspellz and Luji also made good points.