Are you sure IBM didn't care about 8080 compatibility? The PC was released in August 1981, a full 4 years before any of the other machines you speak of. That XT 5160-078 you speak of is a cost-reduced model with no hard drive from IBM, allowing dealers to install a compatible hard drive from a different supplier.
By 1985, the PC AT (286) had already been out since August 1984. And the original XT was October of 1983. And the XT itself is literally the same as a PC with more expandability: 8 slots instead of 5, beefier PSU, room for a hard drive.
It's unclear if IBM or for that matter anyone would have been able to start designing a 68000-based machine and bring it to market by the fall of 1981. Sun brought the Sun 1 to market in May 1982, so about 9 months later, and with a much higher price.
And what did the Sun run? UNIX. What did IBM run? Quick ports of the last several years of CP/M software made possible because DOS 1 was specifically designed to implement a CP/M-like API, and the 8086 was specifically designed to allow porting of 8080 assembler code directly to small model 8086 code.
By 1985, the PC AT (286) had already been out since August 1984. And the original XT was October of 1983. And the XT itself is literally the same as a PC with more expandability: 8 slots instead of 5, beefier PSU, room for a hard drive.
It's unclear if IBM or for that matter anyone would have been able to start designing a 68000-based machine and bring it to market by the fall of 1981. Sun brought the Sun 1 to market in May 1982, so about 9 months later, and with a much higher price.
And what did the Sun run? UNIX. What did IBM run? Quick ports of the last several years of CP/M software made possible because DOS 1 was specifically designed to implement a CP/M-like API, and the 8086 was specifically designed to allow porting of 8080 assembler code directly to small model 8086 code.