I'm not sure that's true, though it's a counterfactual so hard to prove either way. I think without Wintel, probably we would've had more competition and innovation in the area, and cheaper/faster machines. There was plenty of speeding up and broadening of home-computer access before Wintel came on the scene, with competition between Amiga, Atari, Apple, etc. And even in Wintel, innovation sped up noticeably once AMD managed to temporarily break Intel's stranglehold, and inject a bit of competition into the x86 market.