Back in the day, system run levels were seen as desirable. SysVinit went in on that concept to the max. So, if the concept of run levels isn't clear to the student beforehand, the init system for making it happen would therefore be mystifying and maybe even inscrutible.

Runlevels may be an interesting idea (e.g. the single-user maintenance level). But a bunch of shell scripts, each complex enough to support different commands, sort-of-declare dependencies, etc, is not such a great idea. A Makefile describing runlevels and service dependencies would be a cleaner design (not necessarily a nicer implementation).