While I think systemd is a great init system (as well as some other components under the systemd umbrella), I really dislike when components up in the stack hard-depend on it. We can't use GNOME, plasma-login-manager, and soon Flatpak without systemd. Maybe systemd should have been an API + a spec instead of an unportable implementation.
I never tested this myself, as I also dislike GNOME3 from a UI view (I am fine with mate-desktop though), but I found this to be epic from the Gentoo folks - a single man flipping a finger to the systemd devs. The underdog winning the fight.
A shame gentoo kind of went into its own hole for years ...