Embora Hugues Chabot fornecesse um link, a solução desse link veio mais tarde. Então, cito a resposta que fornece uma solução fácil e atualizada:
ArchWiki wrote: For cups 2.0.0, the service name has been changed to org.cups.cupsd.service instead of cups.service. This package is available in extra from October 31, 2014. When upgrading to version 2.0.0, it is necessary to manually disable the old service, otherwise broken symbolic links will be left in /etc/systemd/system/ subdirectories and systemd will warn about non-existent services.
Então a solução é:
systemctl enable org.cups.cupsd.service