I have hacked a considerable amount in both Elisp and CL and I can state that I actually prefer the way Elisp does some things over the way Common Lisp does--this is not to say that CL does things the wrong way--the matter is that they have different purposes. Emacs combined with Elisp in itself constitutes a complete programming system; all of its components are designed around it.
The language being integrated into Emacs makes writing Elisp programs a very fluid and intuitive experience: things like the fact that the documentation and the place where a function was defined is available at any time makes /understanding/ the system easy, and the actual documentation itself is often quite well written, and the Info manuals will most often explain everything you need to know about a package. Common Lisp+SLIME shares some of this convenience, but not to the extent that Elisp truly does.
Certain points like the fact that Emacs isn't multithreaded are thrown around by people who don't have the intuition that multithreading isn't the right thing for a lot of applications. The added complexity that multithreading would add to Emacs would seriously outweigh the usefulness it would provide. Emacs already has a decent process model, and having to deal with only a single shared state makes programs much cleaner.
At the very least if it all comes down to a dick measuring contest, the base GNU Emacs provides 100000000x more utility in its packages in a fraction of the memory space than VS code or Vim ever will. Emacs has its fair share of killer apps like Magit that provide such a clean interface to something that it makes using it worth it for that alone.