It absolutely is enough, though. A job identity doesn't need to give you a strict advantage. It needs to give you a unique gameplay experience.
I started out tanking on warrior tanks in Warcraft some 12 years ago. Back then, the thing that interested me was their sheer mobility. Charge to an enemy. Intercept back to an ally. It didn't really matter to me if this mobility translated into a gameplay advantage or made my class into a must pick. I felt like I controlled the battlefield. It felt unique. And most importantly, it felt fun.
When DRK was first introduced in Heavensward, we had a lot of unique flair. DRK felt fast, and so, so mobile. We had an attack between every attack. You hit us, we hit you back. Stormblood eroded this in nearly every area. The role action system either gave away or removed most of our counter-attack moves. Onslaught gives WAR double the amount of mobility that we have. The sheer amount of knockbacks this expansion make this painfully obvious. Dark Arts feels like molasses, and doesn't feel nearly as good as throwing in a kick or stab weaved in-between every other attack. Our reprisal is now everyone's reprisal. I don't mind that we're behind the other two tanks in terms of performance. What I do object to is being robbed of all of our unique traits, simply because players maining other tank jobs were too greedy. Enough is enough. Get out of our space.
Fell cleave is sacrosanct. If Bloodspiller or Holy Spirit did more damage, WAR mains would lose their minds over it. I want something that is uniquely "owned" by DRK. I think that there are two natural areas for this. The first is speed. The second is resource draining, be it HP, MP, or blood. I want to see lots and lots of green numbers. This is our space.
And if there's a new gunblade-based tank next expansion, they would do well to kick WAR right out of the mobility department. If we're going to keep introducing new tanks and healers, you simply cannot afford to have one tank which can do everything.