Interesting side note. It took years for PC users to gain multi-user capabilities, mostly when with Novell connected machines and brought file/record locking etc. And before the PC multiuser was already in MP/M and Unix on machines like Altos and Molecular Computer. Killdall would have probably got eht market back if he hadn't died.
And fast forward today, deep down Windows still runs much DOS code. Like Veeger it's morphed into Windows whatever.