You cannot do all, or even most, of what systemd does in a loosely-coupled way. Even the supposedly-simple job of (re)starting a daemon in a consistent environment (i.e.. one that's the same as being run during system startup) cannot be reliably done any more – unless you're PID 1.
You know … either prove me wrong with actual code, or shut up.
Or at least stop replying selectively. (As if nobody else would notice.)