Hm, I don't disagree with your points.
But the two examples we have discussed so far, both have a common theme where we have commented on the mental state of the pianist being either affected or unstable.
Maybe that's why. Piano playing is equally about the fingers as the brain, and why even their worst performance could be better than one of our best, it doesn't compare to the guys at the top of their game.
Plus pianists peak, just like a footballer, a singer, a driver, they all require very different aspects mentally and physically, but everybody peaks, and unfortunately it can be difficult to deal with the decline.