>...everyone seemed to be perfectly okay with init until systemd came along...

Everyone was definitely not OK with sysV init. That was the problem. The distros extended it in various incompatible and not very good ways. Regular sysV init was OK for what it did but hardly anyone used it that way. Systemd was not a rewrite of sysV; it was its own thing.

The question of how to do stuff in a Unix like OS is still very much open, making systemd did not magically make the question go away.