Tbf if you look at all the printer drivers out there. You know why they dropped it. PPD is also not a good standard. I mean it would not be too bad, but what printer developers do to make their shitty printers work… (like adding binary command filters and stuff, binary tray mgmt extensions…) xerox for one example ships really strange drivers. Most of the time I use their windows ppd and strip the binary stuff.
CUPS is still the only print system macOS has. Apple never dropped it in the sense of ceasing to use it! "They dropped it" only in the sense of more or less ceasing to maintain it-- there was only one commit in the course of about a year, and no patches accepted from outside contributors at that time-- until it eventually had to be forked.
The name stands for Common Unix Printing System, and Apple CUPS ceased to meaningfully be that after its author left the company. But Apple still uses CUPS in their operating systems!