You can play this semantic game with every class in the game, and every class that ever will be in the game. In the end all we have is ranged dps and melee dps and healing. Tanks, DPS, healers. Ranged, Melee.
The whole trick here is in how much of any one thing you do and how much of any one thing you don't do, and how to make doing the same things feel new. You're blind to this apparently. Your own point shoots yourself in the foot here. And you proclaim your opinion as fact, bravo.
What brings anything to the table at all and why?
What anything brings to the table will be how fun it is to do what it's doing and how it feels to be doing what's it doing. Not if as you're trying to make it seem here that on paper the description of what it's doing is exactly the same thing. Compare how the same classes feel in Diablo 3 to WOW just for starters. It's not a 1:1 format to compare, but it makes the point. A barbarian in D3 is basically doing everything a warrior does in WOW, but it feels incredibly visceral and totally brand new. The howling, the satisfying crunch of bone and tissue and the waves of enemies ground up in the meat grinder that is your blade.
Compared Illidan in Heroes of the Storm to Warcraft 3. Compare anyone in Heroes of the Storm to their former incarnations.
Compare casting a fireball with a mage and casting a fireball with a warlock.
Get something fucking straight here. You can have something doing the same essential basic thing when you write down "swings sword around" on paper but execute it in a brand new way that makes it feel brand new and 10 times more fun based on this thing called nuance and execution.
Dots are just dots. But watching your enemy scream as his head slowly boils and expands and then explodes dramatically is totally different than watching negative numbers tick off until his auto death animation plays.
EXECUTION IS EVERYTHING
Name a single class concept that brings something new to the table here and why it's new. It's all the same stuff dressed up in novel ways, with more tactile and visceral sound DX and solid distinct animations.
The recourse mechanic is really key to WOW's classes and how new they feel. It's a minigame. Mana upkeep, runes, rage, energy.
Every class has a game within a game in this glorified slot machine we call and RPG. What makes it more than a slot machine? A world, avatars you can move around like a puppet in a place shared with other humans.