They tried Windows on Itanium and on Alpha. I think the biggest issue is even though the OS could be recompiled, most apps are not compiled at install in order to take advantage of the underlying platform. You saw a similar issue with the original Surface being ARM only. Sure the OS was there but people couldn’t run the Windows apps they were used to and Microsoft got held responsible rather than the developers.
Alternatively you’d have to put an x86 emulation layer which would slow apps down and people would again ask “why?”
One of the great advantages of software distributed with the source code is the flexibility to move to different platforms and architectures. I wonder if moving to a snap/flatpak model will change this flexibility in the future.
Microsoft has always embraced their own migration. They converted their apps to UWP. They’re making them platform agnostic with webview2. If you want to run just their software on any architecture that’s fine, but Windows and x86 have been co-mingled and anyone who installs Windows expects their 3rd party software to just work.