Please do not conflate MacLisp and Emacs Lisp, they are different languages. GNU Emacs is not directly derived from Multics Emacs, it's one of the many reimplementations of the original Emacs. The closest thing to MacLisp today is actually Common Lisp, and it's much more advanced than Emacs Lisp, which is not surprising considering that Stallman was not interested in creating a state-of-the-art Lisp implementation with his limited resources but wanted to merely provide a minimal foundation for a programmable text editor.