Hacker News Reader

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.

I looked at this once, and I seem to recall SMF relies on a Solaris-specific IPC mechanism with no simple analog on Linux

https://en.wikipedia.org/wiki/Doors_(computing)

As I recall, it was a mess of XML files you edit and slow Java based tooling.