Windows 1.0 came out in 1985, only one year after the Apple Macintosh. PARC invented the idea of the WIMP GUI, not Apple. I think it's a little silly to say that the idea would have died within PARC.
Th idea of WIMP really wasn't "invented" at PARC. That organisation gets way too much credit. They amalgamated several concepts that had been developed since the late 1940's. I'm not suggesting that PARC's work wasn't important, but to blithely dismiss Apple's contribution and suggest that it all started with PARC it ridiculous.
Go and learn about Vannevar Bush and Memex, Ivan Sutherland and Sketchpad, Doug Engelbart and his contributions like the the Mouse and his oN-Line System. The history of modern computing is simply not as black and white as you are trying to portray.
Finally, anyone that has used both Windows 1.0 (and 2.0 for that matter) will tell you just how awful it was, especially when compared to the Macintosh. Microsoft didn't come close to the ideas presented in the Mac until 1990 with Windows 3.0, and arguably it was the 3.1 release in 1992 that was useable.
