> I've been using and programming Emacs for ~12 years. After all this time, I am at the level where it really feels like an extension of myself...
The problem is that these days, you could use vscode or atom for a month or two, and get that same feeling. Emacs from scratch is not a great use of time anymore.
Maybe so, but the ceiling with those tools is very low. I simply can not do what I do every day with Emacs using vscode or atom. I know why you compared them, but I feel that these comparisons are meaningless. A category error.
What are some examples? I'd say the ceiling is marginally lower (maybe) than emacs, but the learning curve to extend is orders of magnitude more approachable.
Almost everything I do on the computer happens inside Emacs, using programs written in Emacs Lisp:
Writing code, reading/sending email across ~30 email accounts spread out over different services, reading newsgroups, mailing lists and RSS feeds, maintaining a presence in 7 different IRC servers with ~30 channels total, using a variety of connection methods, watching and filtering certain twitter feeds, controlling external applications through Apple Events [1], file management local and remote, remote system management, local virtual machine management, note taking, calendar, agenda, notifications, bookmarks for external applications (Chrome and Preview), password manager, version control, music playing.
I can keep going. The only programs besides the OS and Emacs I use on a regular basis are Google Chrome, Preview.app, VMWare, Calibre, mpv, bash/ssh, Unix command line tools (less and less) and my bittorrent client written in Common Lisp.
I've almost finished an Emacs Lisp controller for Chrome, allowing me to bring a lot of information (e.g. tabs) into Emacs in order to rapidly manage it on my terms. I've done the same for Preview.app. I treat it as a dumb vessel that does the rendering. The actual information (filename, metadata, current page, date etc) is extracted from it, stored and manipulated in Emacs. That way I don't rely on Apple to dictate how I'm allowed to use my computer. I can experiment with different paradigms and find the one that fits me best. Emacs is the magic that makes all of that happen.
That speaks to the general breadth of the emacs extension/package ecosystem, which is impressive (but somehow not as impressive as you'd like), but how many of these things did you engineer yourself? And how many these things could not be implemented in modern editors? I'm not sure any couldn't be. Most already are.
Extensibility was emacs' killer feature when its main competition was vim and vimscript - that's just not the situation anymore.
Emacs main competition in the noumenal realm of ideas wasn't vim, but the commercial Lisp Machines mainly Symbolics. They were superior but technical superiority doesn't mean much in the domain of "Worse is Better" [1].
I didn't write all of the Emacs Lisp programs I mentioned, but I did go through most of them, changing the way they work to fit how I wanted to use them. This was an iterative process that is still ongoing.
What should impress you is not the breadth, but the paradigm itself as expressed in Lisp. You can probably write an IRC client in JavaScript and have it in VSCode. But that's not what I'm talking about. We're not ticking boxes down a feature list here to say "JavaScript can do that!". We're talking about a paradigm, and specifically about interactive development with a short feedback loop through Lisp which is "a difference that makes a difference" [2]. But in order to truly understand this, you have to go through the process. Philosophical truths can not be transmitted like pieces of eight.
VSCode is quite restrictive in how it can be extended actually.
Atom is much better, and feels closer to Emacs in terms of allowing you to extend and modify almost every part of it.
That said, Emacs is just the king. Not only can you really just change absolutely everything, it is really easy to modify it all at run-time on the fly, which even in Atoms isn't quite so.
I had settled on Atom for a while, but the slow performance and high memory use made me switch to Emacs.
The problem is that these days, you could use vscode or atom for a month or two, and get that same feeling. Emacs from scratch is not a great use of time anymore.