Vim is (like GNU Nano or GNU emacs) lightweight. It does not need any kind of graphical interface (like x11, wayland &co).
This makes vim to a system maintainers best friend. You can use it using ssh and, this is really important, on really small devices that do not have some kind of graphical interface.
Programming on and maintaining remote servers got more and more important during the last years and using vim (or emacs) is the best way to do so.
Unlike many IDEs vim brings the capability to work with many kinds of files out of the box and writing your own commands and syntax hl is easy.
And last but not least, a vim user should be able to use vi, that is preinstalled on most UNIX systems.