"I thought it was a joke operating system from the 1940s"
Citation needed for operating systems, joke or otherwise, from the 1940s.
"when I first worked on it in the late 1980s."
Hmm. Back then I'd been involved in using Unix for casework administration in a busy forensic science lab, distribution & service of mobiles, administering social housing, administering a professional society's membership list & maybe other stuff I've forgotten. And many other people were using it for many other applications. So what was your problem? PEBCAK?