Unfortunate, considering a lot of it is wrong. "Just so" stories (a term from Kipling) are appealing and yet historically incorrect.

For instance, /sbin and /usr/sbin/ did not exist in the 1970s at all, let alone in the early 1970s.

I'm not sure exactly which system it first appeared in, but on BSD, which originally was add-ons to the Bell Labs distribution, it was not present in the 1986 4.3 BSD but did appear in the 1993 4.4 BSD.

You can verify that, and search for it on other early Unixes, here, for instance:

http://minnie.tuhs.org/cgi-bin/utree.pl

OK, it gets a couple small details wrong, but the rest appears to be true - that /usr was added for want of disk space and /sbin was for statically linked binaries.

The point of passing this along is to show that some ingrained "truths" (ex: sbin is for system binaries!) are just historical artifacts of conditions that no longer apply.