It’s not as clear cut as that. There was a non-Microsoft DOS (might have been Dr DOS but I can’t recall specifically) that would boot Windows 95. Then Microsoft released an update that caused Windows 95 to fail with an vague error message intending to deceive users into thinking there was a technical limitation in other DOSs that prevented Windows from booting. Yet it was later proved that limitation didn’t exist and all Windows was doing was checking if it was MS-DOS, and if not returning an error.

If I recall correctly this case even went to court.