I'm not going to argue that emacs if "for everyone" and there's plenty in my own life that I'm happy to accept defaults in. But that said, it's not that hard to glue emacs onto existing tools if needed. If you're in a situation where you can only send emails on a locked down email client you can still script the client through emacs and some glue code. On MacOS, Apple script does wonders and for Windows there's AutoHotKey. Linux obviously is infinitely malleable.