Thing is, though, most of those things are different systems. systemd-logind systemd, systemd-udevd, and journald (and others) are different systems in the same

Thing is, though, most of those things are different systems. systemd-logind systemd, systemd-udevd, and journald (and others) are different systems in the same project. They're a bit tied together (through dbus and I'm not sure what else), but that doesn't mean they're the same system.