[mcncm]

Despite being a plain-text format, it can be made very human-readable with minimal configuration. If you want to auto-export to your preferred format on save, say, and view it live in a parallel window, you can accomplish that with a single line of Emacs Lisp. This is what Emacs is all about: if you can do anything with a tiny little elisp function, there isn't exactly a clear bulleted list of what the "features" of an application are. Some people really like that.