This narrative doesn’t jive with the Windows NT development history and its support for Alpha, PowerPC, etc. As well as Windows CE historical range of processor support.
It is a common view that the "wintel" architecture "monopoly" sucked investment that could feed other more efficient architectures than x86. It is known that NT supported many different architectures, mostly thanks to its VMS heritage, and CE supported POWER and even ARM. But as soon as the desktop became the strongest cash cow, I think other options were kept mostly as lifeboat options.