Microsoft can switch architectures though. I have an ARM64 Windows VM on my M1 mac. It runs x86 executables seamlessly and fast enough that you don't even notice that there's an emulation/translation layer underneath.
The Windows 9x series (and earlier) were tightly coupled with x86 (and DOS).
The Windows NT family of operating systems has always had the "Hardware Abstraction Layer" (aka HAL) which helped with porting the operating system to other architectures.
