Gary Kildall recreated PIP for CP/M because he had come from using Digital/DEC systems. It wasn't just RSX-11, it was in a bunch of PDP stuff going back.

It was a pretty "revolutionary" feature of Unix that device I/O was just in the filesystem along with everything else so all software could access devices. (Not claiming revolutionary as in invented, revolutionary as in one of the things that helped unix achieve ubiquity and would be the first place most people saw it. Maybe it came from Multics, I don't recall.) Without filesystem mapped I/O, you need to create peripheral interchange programs to do ordinary things like copy files and print. Once you get used to PIP style file specification on command lines, it's a next step to push it into the OS API, so CON: will always mean the console, rather than only to software like PIP. This is the origin of MS-DOS having those special names too.

And colon as a special character in a file specification (I didn't say filename) is not just Windows, it's also in Unix (that's where it came from in http:), that's why I'm astonished to hear that people are naming files with colons in them. It used to be, there were more experienced people you worked with who would teach you very quickly that you don't put colons in filenames. Those days are gone, it's emojis all the way down, including some very sad emojis.