Right now, if you run "systemctl disable systemd-logind.service", you just see the normal "rm" line for the /etc symlink. This implies the command ran properly, disabling the service. Unfortunately, the symlink for systemd-logind.service is hard-coded in /usr/lib/systemd/system/multi-user.wants, which won't get affected.
Perhaps we should have the command say something about needing to mask the service to fully disable it, much as socket-activated services, when you stop them, give you extra information about how they can restart on connections.
*** This bug has been marked as a duplicate of bug 56690 ***