MS made significant changes to DOS before they gave it to IBM. They worked day and night for months to get it ready. Even then, they gave Killdal the right to the result. Killdal simply did nothing with it.
Basically, they snookered him. “Here you go, Gary...we’ll give everyone who buys an IBM PC the option of PC DOS or CP/M.” Of course they didn’t tell him that DOS was going to be bundled in for $40 but CP/M was going to cost $240. Gates and Co. were much better at conning and scamming people than they were at innovation.