My desktop ran Enlightenment 0.15 around 1999. It was a hundred times more beautiful and usable than anything Windows could offer at the time (including stardock/windowblinds). It was less usable for non technical people, but it was usable and the horrible IE lock-in has not yet happened at that point.

Competition is good, but it is entirely speculation whether windows promoted or stalled progress by virtue of being a monopoly; my vote is “stalled”.