the article would be improved if they addressed the historical facts of typewriters, telegrams, teletypes, and ASCII instead of just presenting this view which is typesetting and unicode. (could also mention fixed pitch vs variable pitch/proportional spacing)
typing on a typewriter or computer keyboard (without fancy multi-key workarounds), you can't distinguish between a hyphen and an n-dash (not to mention the minus sign); you use the same hyphen key for all those, and represent an m-dash with two--hyphens. That's the starting place for most people who will read this article, and that should be the starting place for the article, if only to say "everything you thought you knew is wrong, here's how typesetting works..."
And, to tell you the truth, while reliably using em-dashes in a word processor. I mostly just use hyphens on a mostly text site (or even an email) and don't bother with en-dashes at all. I guess I use em-dashes for formal/fancy stuff.
typing on a typewriter or computer keyboard (without fancy multi-key workarounds), you can't distinguish between a hyphen and an n-dash (not to mention the minus sign); you use the same hyphen key for all those, and represent an m-dash with two--hyphens. That's the starting place for most people who will read this article, and that should be the starting place for the article, if only to say "everything you thought you knew is wrong, here's how typesetting works..."