CUPS is great when you have a printer with a weird driver that you can only get from the manufacturers website. A few minutes setting up a CUPS VM, install the printer driver, and now I can print from my phone.
Oh I know, (sysadmin here) but it has a host of other problems. For example security wise, distro specific quirks etc. I do have to acknowledge it has worked when nothing else has sometimes, and I liked how easy it was to use with samba. Also I prefer IPP these days, at least when stuck dealing with windows clients.