A constant theme here at Irreal is that one of Emacs’ virtues is its programmability. Not the ersatz programmability offered by VS Code or even Vim but real programmability. You can introduce new code or change old code while Emacs is running in a seamless manner.
But why is that so important? Aren’t knobs and check boxes enough? Positron has a nice video that provides the answer. The TL;DR is that, no, knobs and check boxes are not enough. They’re more complex to implement and maintain, they quickly go out of date, and they simply aren’t as flexible. With programmability, the user is in charge and can evolve the action of Emacs as needs change.
Positron makes a good point about Elisp and its supposed slowness. The code you write for Emacs happens, as Positron puts it, at the other end of the keyboard and therefore at human speed. It doesn’t matter if it’s slower than C or whatever. It’s fast enough for human senses. For those jobs that require more powerful computation, Emacs simply subcontracts them out to an external process for faster processing.
As far as I know, only Lisp Machines and their descendants offer this kind of programmability. Today, the only widely used piece of software that can do this is Emacs. To me it seems not so much an advantage as a necessity.
It’s a short video (4 minutes, 35 seconds) so take a look. Positron makes some good points.