It was code that even let one make simple files to start up one shot process or daemons. If a long running daemon died it would restart it. Plus it handled the getting the status of orphaned processes, and few other things.

Really the biggest issue with systemd is is scope creep scope creep means more and more packages will have systemd as a hard dependency. Like there some aspects of gnome that will not work without systemd, but at least it's not entirely a hard dependency just means you lose features unless you patch gnome.