Who?

1. People who do most of their work in the terminal and don't need a full IDE for editing their config files. A subset of those imo would be those who have lots of different servers they ssh into and like to have the same (or similar) editor everywhere. (vi and vim for example)

2. They like a more lightweight editor. Being able to configure anything relatively easily if you know what you're doing would probably also fill into this.

3. People who primarily use keyboard based navigation and like not having to move their hands as often. I count myself to this group, as I recently discovered doom-emacs and absolutely love the keybindings it has. (vim keys for navigation. Functions are handled by the spacebar and a key combination)

Nerds.

And people with fewer options. There are plenty of situations where you are stuck with Vim or Nano (Vim usually comes out on top if you're doing anything non-trivial).