But these are hard deps not just recommends so will pull in systemd dependencies regardless of it using them or not. If it were a recomends type dep, again no one would have a problem. It used to be considered bad packaging to hard dep when recommends or suggests would suffice.
7.2 states: "When selecting which level of dependency to use you should consider how important the depended-on package is to the functionality of the one declaring the dependency"
You say "being able to use software under another init system." Looks like the level of dependency should be adjusted to fit your point.
You might want to learn how shared libraries work under Linux. Then you might be able to understand why packages have a Depends: libsystemd0 (which btw. doesn't depend on systemd itself).
7.2 states: "When selecting which level of dependency to use you should consider how important the depended-on package is to the functionality of the one declaring the dependency"
You say "being able to use software under another init system." Looks like the level of dependency should be adjusted to fit your point.