I honestly have no idea what you're talking about. The idea that UNIXes diverge from either BSD or SysV is not controversial. The fact that virtually every commercial UNIX had a completely different set of administration tools (other than vxfs as a add-on product to many) for any and every administrative task and init scripts in different locations are not orthogonal. "This system derives from SysV and that system derives from SysV, so I can administer them the same way" is complete bollocks and always was, even down to the location of the init scripts. That's the point.

At no point did I make any claim that inittab+runlevels was the "only thing going". I claimed that many systemd detractors hold to some abstract idea of a "pure" UNIX which never existed in the first place. As mentioned in my last comment (or my first comment) recognizing that there are fundamental limitations to traditional init and replacing or supplementing it with whatever (SAF, srcmstr, openrc, initng, you name it) and "being like systemd" are not even remotely the same thing except that they both manage service initialization.

This kind of false dichotomy is the point of the original post, which you missed in your fervor to turn it into a strawman. launchd, upstart, smf, runit, and other modern replacements are also not "like systemd" except that they manage services. SRC didn't replace init _at all_. It was a system run in parallel, as you well know. It was not a replacement for sysvinit, and AIX still has sysvinit. Again, as you well know, but it doesn't fit your narrative.