It's not arbitrary. There are logical security, reliability and convention boundaries that systemd doesn't consider which are raised in this article. Microkern

It's not arbitrary. There are logical security, reliability and convention boundaries that systemd doesn't consider which are raised in this article. Microkernels are a different subject altogether. To be honest, the only service management solution I've seen that I actually like for Unix platforms is BSD's simple rc and daemontools on top of it for process management.