I used Linux (and some Unix) before systemd was a thing and init scripts are jank. So much boilerplate and that was before things like proper isolation existed and other more modern features.
I don’t understand why anyone would want that back.
A replacement of systemd with something else would be fine, but please no more init scripts and pointless run levels.
I almost forgot it existed. It was a slight improvement, but with a whole bunch of new problems (most notable race conditions which were never fixed) and it was made obsolete by systemd.
It was a good evolutionary step only used by Ubuntu iirc. It was better at that time than the previous init system, but not more than that and it never found wide adaption.