Rename File in Emacs
First impression people have is that Emacs is an editor.
So in an editor one should just save as to different name/path. 1
But save as is different from renaming a file. save as creates a copy
of the file with a different name/path. So one has two files with old and new
paths.
But rename leaves just one file at thenew path.
Older versions of Emacs (< Emacs 26) did not have this functionality built-in
So either one had to use dired or people wrote their own functions.