I don't think unified mechanics is good for its own sake. Mechanics should support the thing they are trying to emulate. Sometimes that works with a unified core mechanic. But sometimes you need something bespoke to get it right.
But do they do anything about it.
3.x had much more robust 3 pillar support. But that's obvious: 3.x had much better overall support.
I guess one thing I dislike is the low level of support overall. Despite more customers than ever by orders of magnitude, we get very little support.
I think the fiction is usually ducking behind a thing or throwing yourself to the ground or putting up a shield just in time.
That said, what if an AoE Dex save was a Reaction but you could move half your speed?
Have you never seen an action movie?
Improvement is always on a continuum. You will NEVER improve by 10 pounds in one day. You train to get stronger and then one day you push your PR. When you test that determines how much you improved.
You are arguing against a position no one has taken.
To be clear, I was never arguing that DH was grimdark. I was arguing against the idea, actually. But I still think the Scar death spiral is somewhere in the neighborhood, and 5E does not have something similar against maybe permanent ability damage but I have never seen it happen in 10 years...
I don't think you are appreciating the combat impact of running out of stress. It means no more beating Thresholds. it means using adversary and environment abilities to cause stress and just doing damage.
Also, exhaustion is an okay system for representing "tired" but IME barely comes up. in...