I may be wrong, but isn't it that systemd also depends on things like dbus?
Systemd uses the D-Bus protocol for communication (e.g. between the systemctl client and the PID 1 daemon), but a minimal systemd install does not require the D-Bus daemon. That said, you'll be hard pressed to find a Linux desktop systems or server without the D-Bus daemon (no matter what init system is in use), but it'd certainly be possible to build an embedded Linux system with systemd init, and no D-Bus daemon.
Even though it might be possible to run systemd in a sane way, distributions now package it with all sorts of crap.
Really? Ubuntu now ships with systemd service management and the journal (and, yes, udev and the D-Bus daemon, though those have been included for a decade or so). AFAIK, Ubuntu also uses systemd-logind (though it used that even before it switched to systemd init), and doesn't use systemd-networkd (but sticks to NetworkManager), nor does it use systemd's DHCP or NTP services.