> Also, around 2001 was the big architectural change for desktop from DOS to NT, so this might seem like cherry-picking the timeframe selected.
It's true that the entire Windows product family converged onto the NT codebase with the release of Windows XP, but this isn't really relevant -- Windows executables and DOS executables were always different things, and despite being built on top of a DOS-based kernel, Windows 9x still supported the same Win32 binaries that ran under NT.
There was even an extension called Win32S that allowed Win32 executables to be run under Windows 3.1. The Win32 API dates to the early '90s, and modern implementations do support executables dating all the way back to the beginning.
Barely - most bigger programs did not adhere to all standards, but got custom fixes under the hood in follow-up windows versions.
Also, around 2001 was the big architectural change for desktop from DOS to NT, so this might seem like cherry-picking the timeframe selected.