> a lot of 70s and 80s "Unixes" don't exactly resemble what we think of as "Unix" anyway.

As someone who was a UNIX developer (both kernel and userland) working for a UNIX support shop (Interactive Systems Corporation, later bought by Kodak and then Sun) from the mid 70's, starting with UNIX 6, through the late 80's and once gave a Usenix talk called "Everything you wanted to know about System V but were afraid to ask", where I held up the white System III manual and the black System V manual and joked that they had gone to the dark side, I find this comment utterly nonsensical. I can look through today's BSD man pages, or its code, and it's very familiar.

> If instead you think of SysVR4 as the first "Unix"

But of course it wasn't.