A sign of the success of the EMACS design is that EMACS has been requested by over a hundred sites and imitated at least ten times.
The extensibility of EMACS is the point, not the key commands. Any editor where interpreter facilities are always available at runtime could (more or less) do the same thing.
One argument made was that because Emacs was written in Lisp, it pulled Lisp from the ivory towers into systems programming. Not sure I agree with that one totally (especially given the jankiness of Emacs Lisp), but it’s an interesting use of it.