These things were studied in decades past. Did you demand research and stats when Microsoft made it impossible to tell which window is focused? What benefits were claimed?
I don't use windows, I don't like it, but if [it being impossible to tell which window is focussed] doesn't impede people accomplishing the things they need to do, it's probably a cosmetic, at best a minor usability problem.
You seem very invested in dismissing constructive criticism. And you demanded research but provided none.