Every <program>-s6 package adds two directories on /etc/s6/sv, <program>-srv and <program>-log. However, CUPS has its own logging system and it will automatically log print events and access errors to files inside /var/log/cups, whereas the cupsd-log service creates /var/log/cupsd, which remains empty. Why does the cups-s6 package include the cupsd-log service? Does cupsd ever write to stdout so that it can be logged by that service?
Because I was just mass adding a bunch of stuff at once without really thinking much about it. :P You're right that it's pointless though. It logs literally nothing. I'll remove it soon.
Should be gone now.