Windows isn't fixable because Microsoft isn't fixable.
Microsoft's biggest and most consistent product is contempt for its users - consumers especially, but also business users.
When you understand that all of Microsoft's offerings are vectors for that contempt, the rest falls into place.
A user-centric Microsoft is an oxymoron. The company is literally incapable of it.
You're probably correct. Windows can be fixed, but it's stuck in the hands of MS who never will, so true ideas on how to fix it are little more than intellectual exercises.