> Emacs also has a built in email client, RSS reader, IRC client, calculator, file browser, web browser, markup language, regex DSL, Vim emulator, terminal emulator, custom elisp based shell, interactive REPL that works for several programming languages...
Then most of these things are not in "emacs" since most of them are packages and not builtin. That was my point. Emacs is insanely customizable through packages, and can essentially run anything. Chrome and Firefox and any other web browser are also insanely customizable through "packages" which you just so happen to download as soon as you enter the URL to the "package" you want, which we really refer to as a web app. But, that doesn't make the browser an OS, and it doesn't make emacs an OS either.
