Hold on. Operating systems and long-running esoteric history are always on topic here, right?
(This is spoken with something close to affection; I look fondly on my former Emacs days. I'm probably more likely than not to enjoy the company of a human who has at least tried Emacs and had some thoughtful reaction to it. I may not use it now, but the ideas live on in how I think and what I expect. Editors that push the limits, whatever those limits are, are part of the old school ethos I love about programming.)
I think the "Scripting language? Check!" is missing an important distinctions between Emacs and most other extensible editors. The proportion of the code editor features that are written in the configuration/extension language matters
Looking at the Emacs and NeoVim codebases in GitHub: Emacs is 74.6% ELisp or CommonLisp and NeoVim is 71.9% Lua or VimScript. Never mind, NeoVim is close!
But, can you at runtime modify the NeoVim core functions? Honest question because I've only used vim and VimScript was definately limited compared to elisp. If so, then I say NeoVim and Emacs are both highly-extensible editors.
None of those capture the essence of emacs, which is that it is a scripting language repl where the vast majority of functionality is implemented in that language and can be inspected, debugged and modified at runtime.
Emacs is a general purpose programming/computing environment that ships with a text editor and some other nice features. Vim is a text editor and some other nice features that ships with a scripting mechanism. Not the same thing.
Vim has stopped before that particular threshold. But if ever Neovim get a GUI version, I believe the community will soon have its own Gnus, Eww, and EMMS.
I am working on a modal code editor project that you might find interesting then. It also operates on an AST directly, which is represented as UI nodes which closely resemble normal text layout. Email in profile if you’d like to give it a try and possibly give early feedback (still in early development).
1. Orthodox. Mostly focused on looks and integrations.
2. Modal, Vim improvement. Focus on keeping basic Vim keybindings with minor improvements.
3. Modal, rethinking Vim approach.
Ki falls into the third category which I constantly monitor.