I don’t know, I think the concept of a BIOS with a documented API and the included minimal component set (e.g. serial port, parallel port) raised the bar on what third party software could assume existed and could be accessed over the existing 8-bit computers if the time.

The IBM PC did not include a serial or parallel port. Just a keyboard port and a cassette port (the latter of which approximately nobody used)

CP/M had a BIOS with a documented API.