I taught an intro database course recently, and only touched on some of that history. It wasn't the main point, and it was an undergrad course.
But you point out a real problem. There is so much reinvention by people who simply don't know what was done previously.
* I have seen research I did in the 70s/80s get redone in the last 20 years, with no awareness that the problem had already been solved.
* I saw a horrifying takedown at an academic conference, (late 80s?) Someone on the original System R research team was pretty furious at a young researcher for being completely oblivious to the fact that he had repeated some System R work. (He blamed the conference reviewers as much as the author.)