They did, it one of the larger parts of systemd that motivated its adoption and ubiquity. A bunch of commercial UNIXes sprung init replacements/extensions with

They did, it one of the larger parts of systemd that motivated its adoption and ubiquity. A bunch of commercial UNIXes sprung init replacements/extensions with process lifetime management systems in the 2000s, systemd is visibly influenced by many of their design choices. OS X natively uses launchd (uses plists for config, has a weak dependency system) , Solaris uses SMF (uses XML for config). There were also the daemontools/runit family, s6, and a couple others that sprung up from open source quarters.