Remember DOS? The operating system, if you could call it that, of the original IBM PC, and MS-DOS, the OS that ran on all the IBM-compatible clones? The PCs that took the market away from Apple? The ones that established Microsoft's monopoly?
The market was different back then. There were a lot of choices, like PC-DOS, and even other computer systems like Mac, Atari, Amiga etc. MS-DOS itself did not give them a monopoly. It was an advantage of course, but not a "competition killer". It could have been IBM's OS/2 that would have "won", or a world with more cross platform development.
