Usability is the wrong metric, paint by numbers is more "usable" (sic accessible) than a canvas but you'd be depressed watching your son graduate art school and that's all he can do.

If you do want to optimize for usability you have to make sure you aren't making the system more consumptive at the same time. The prime example from the article is trading a moment where the user must take initiative with a menu. More useable less useful. Lower the floor not the ceiling etc. Windows (and iOS) did make genuine improvements to OSs but because of decisions like these most users are locked out of enjoying them.