I'm aware of what the difference is. But, and this is really important, you cannot gloss over the static nature of overloaded methods. You say "if someone adds a more specialized overload, it will be called", but that is only true if they recompile.

Generic functions in LISP are another way of doing this. It works at runtime, as well. And that leads to a good article in the elisp manual (https://www.gnu.org/software/emacs/manual/html_node/elisp/Ge...) that shows multiple dispatch being a runtime thing even way back. So, again, I'd be interested to know sources that said multiple dispatch was the same as method overloading.

I think I can see where overloaded methods were likely coopted by single dispatch statically compiled languages. But, honestly, I don't see how "multiple dispatch" would have ever made sense in those cases, either.