[retrac]

CP/M software was (somewhat) portable. That was its killer feature. A program coded in 8080 assembly that closely adhered to the CP/M API, would run on any 8080 machine that could run CP/M. Anyone with the hardware skill could build a CP/M compatible computer, no coding required beyond a bootloader and tweaking the CP/M BIOS (low level driver code). There were dozens of manufacturers of CP/M machines. On the other hand, there was no standard BASIC common across all those machines, besides MS BASIC, sort of.

On proprietary systems, BASIC shells were a thing. Both DOS and ProDOS on the Apple II hooked into the ROM BASIC interpreter.

[donatj]

Just to add a little detail, MS BASIC’s capabilities varied pretty widely across versions and machines, and it wasn’t helped that Commodore had gotten a sweet heart deal on MS BASIC in 1977 that included no royalties and as such they never upgraded the version of MS BASIC - as that would involve giving the now much bigger and more apt Microsoft another whack at the terms.

[InterNautic]

Yes, this is why "it can run CP/M" is popular "form of bragging" among modern homebrew computers builders.