PDF creation apps generally pretend to be a printer so you can “print” a PDF from any app. I’m unsure if they use the spooler, but it makes sense that they might, and I defer to Quartz’s experience.
The main thing is just to remember what you turned off, so you can turn them back on if it turns out you need them later.
Did you also do all the privacy stuff and turn off that junk (as in the instructions I linked above)? That to me is more important. Get rid of the ads, and stop it from phoning home or sharing updates with other computers.
