Emacs is more like an ecosystem around text, so switching keybinding does not matter much. And most people's system is installed on a single computer, very much like Photoshop or Visual Studio. Vim is all about editing text and the keybinding are like a DSL for this purpose, so changing things will make you awkward everywhere.
The clue lies in the fact that you can customize the editing experience to function like Vim. Because that’s one out of a thousand different ways you can customize that app to function like a one-off editor, a Git client, an email reader, and so on.
Vi is like an standard for moving around and editing text files. I use Vi-style commands in all my editors: Emacs, IntelliJ, and VSCode. For me, any application that supports Vi keybindings and has some sort of command palette will feel like home.
Regarding why edit files in Emacs instead of vim: I simply work on Emacs. I don't use a CLI or a file manager to navigate to my files, I already have projects set up in Emacs and can quickly open files in any such projects. Emacs also holds my note taking system. And when I'm dealing with git, nothing comes close to magit. Also, I've been using the Spacemacs framework for years, which makes it really easy to create such a customized and efficient configuration without much hassle.
The reason people like emacs has nothing to do with the default key bindings, which are basically arbitrary. Emacs is a framework and programming environment for building custom IDEs.
You get the vi bindings and modal behaviour which I find better _plus_ all emacs functions and most of the emacs bindings. I’m often mixing the 2 modes while editing.