Emacs could be an IDE, if it came with the whole Lisp Machine for the ride, sadly it is only a subset of the whole experience.
VSCode has zero lines of Atom code into it, it started from Azure as Monaco project.
Does neovim distribution handle graphical development plugins, without spawing external windows?
Yeah, right.
No one but you here cares about prior art. And not even you, most likely, otherwise you would write your in some kind of lisp which was first on most of the things.
> Emacs could be an IDE, if it came with the whole Lisp Machine for the ride, sadly it is only a subset of the whole experience.
Lisp is just an implementation detail in (GNU) Emacs, even though it is what makes it a delight to configure. The rest is done, as everywhere, with plugins and built-in package management.
> VSCode has zero lines of Atom code into it, it started from Azure as Monaco project.
VSCode has everything from Atom in it, since it is basically a rewrite of Atom, using Electron, which was written for Atom.
> Does neovim distribution handle graphical development plugins, without spawing external windows?
What should it be, UML-plugins? Coroner has called, he wants his dead things back. But most stuff is handled with overlays these days with Telescope.
Can I put my cursor on a defun in Visual Studio Code, Eclipse, or IntelliJ, mash C-M-x, and immediately have that functionality available in my running editor session with all my work? I can in Emacs, and that capability has allowed me to smooth out the rough spots in many a workflow.
Lisp is not just an "implementation detail", it's central to what makes Emacs great. GNU Emacs is a running Lisp image, which you can extend and shape at will as you work on something else. A phenomenal tool.
For programming purposes emacs is not that different from any modern editor - there are some built-in capabilities, the rest you get from ELPA/MELPA/Git. It has no proper plugin arhitecture, which is a gift and a curse at the same time, but mostly works out. Where emacs shines compared to vscode/neovim/etc is that it has a very solid support for prose, org-mode, denote and prots color schemes which are that good. It is why I continue to use it, even though I am not interested in lisp per se these days and could easily replace it for programming with any other advanced editor.