Re: I've forgotten...
But more so, systemd has other lovely things it can do on failure, it's not pretty but it is possible to make systemd send an e-mail or run another service, sysvinit has nothing.
Why is that a problem? sysvinit is what it is supposed to be. init.
If you have some processes that may die or need to be restarted should they die, that can be done outside PID 1.
I had an issue (this was probably nearly 30 years ago or something) where I did need some process(es) to stay up no matter what and it wasn't exactly hard to write up a quick watchdog script to check for the processes and restart (and send notification) if they were found not to be running.
You don't need to reinvent init for that.