I've been using EMACS since it was TECO on TOPS-10. Not a day goes by that I don't spend at least an hour with it. But it is long in the tooth and the abstractions it exposes are as advanced as they can be without breaking reverse compatibility. It is one of the few packages I think would be improved by a fully-supported package manager. E-Lisp is a warren of inefficiency, notational paucity and half-implemented tools. If someone wanted to build an emacs-like text editor in Lua or Fennel, I would absolutely sign up as a beta tester (assuming the key bindings were mostly the same.)