A haphazard bunch of shell scripts is not much better than a monolithic binary

If know shell scripts you can read and adapt the former. You can keep the state in vcs without needing a compile artifact or a compiler.

How much work is it to add a bespoke feature to systemd?

It's a tradeoff for sure, but let's not pretend simplicity has no benefits.

And knowledge of Cron transfers to the bsds.