I haven’t read your piece yet, but I searched the page and didn’t find any mention of DEC VMS’s DCL, or Symbolics Genera’s Dynamic Listener.

If you’re talking about how to design a command line for usability, you really need to become familiar with them, as usability and extensibility were explicit design points and they both work very differently than (and much better than) even modern UNIX.

They should have come up in whatever literature search you did prior to writing your piece. At least you can easily investigate both of them via preserved documentation and emulators, if you don’t have access to hardware on which to run them: There’s an x86-64 build of OpenGenera floating around you can run on Linux, and you can run VMS in SIMH. And Kalman Reti did a great demo of Genera on YouTube.