GGP's claim is emacs is better learned as a lisp machine than a text editor, which is akin to saying a monad is just a monoid in the category of endofunctors. GGP's critique is typical of poor exposition. Read the first chapter of any maths textbook from the 1970s. It doesn't make any sense because the author already knows where everything leads and lest he appear a fool to his peers, will insist the reader does too.