They bought Howl software, its developers, and renamed it Bonjour and made it open-source - that became the de-facto standard for their network "plug-n-play" support for devices because Microsoft was trying to convince standards groups to make its (failed) protocol the standard for this.
OSX printer support wasn't bad because of low marketshare. It was bad because it was a new operating system. And it wasn't just printers but everything. Drivers, applications, utilities. They all took years to move to OSX.
And most technologically astute people (young or old) know that OSX relies extensively on UNIX software of which CUPS is just one part.
No, the parent comment is correct.
"It was bad because it was a new operating system." -- it was already bad in the pre-OSX Mac era (mostly due to low marketshare).
"And it wasn't just printers but everything. Drivers, applications, utilities. They all took years to move to OSX." -- for applications and most other things Apple had migration alternatives (Carbon APIs for pre-OSX Mac apps, the Classic environment for emulation of pre-OSX and even Rosetta for emulating PowerPC on Intel).
For the case of printers, they really just dropped whatever they had and went with the Linux solution.
And you try and tell the young people of today that ..... they won't believe you.