I’m sure the irony is not lost on you regarding the fact that systemd can not possibly run on an alternative platform, thus the situation you just ascribed is not “better” with systemd.

Sure. That wasn't in favor of systemd, though? I comfortably write code against the GNU userland and I use systemd where it crops up. Just not a big deal to me; if somebody wanted to use my stuff elsewhere I'd just say "pull requests welcome!". I found the inconsistency striking, that's all.

Checking for content of a variable before passing it to rm is a basic instinct that should be done in all shell scripts. The comment about --preserve-root is just a reminder that the problem of deleting / is very rare.