Dps is damage per second. A dps class focuses on raw damage, nothong else. It can't do anything else. From what we know of the sub classes hunter is a dps class, no matter what sub class your in the only thing you do is damage and lots of it. Titans as tanks fits perfectly with the generalised term for a tank. A high armour, high health character who's job is to get on the enemy's face. Yes there is no aggro table like mmorpgs have but assuming everything is equal on 3 guardians and a boss fires a homing projectile that has to hit a party member which do you choose? The warlock that will likely die outright, the hunter who is going to be critically wounded that they have to hide so not doing any damage or the tanky high armour titan than takes maybe 1/2 or 2/3 of their health? There are no healing sub class, that we know of and even if there was it wouldnt be mmorpg healer, its more like support sub class. While some mmorpg terms aren't applicable most are you just have to understand what people mean by them.