Cute trick, but this is no good. Sure, I overuse the em dash — anyone who’s read anything I’ve written will quickly learn that truth about me. But I think the linked column betrays an impoverished conception of writing. Call it Editor’s Disease: the written word as its own artifact (or, worse, as precursor to embodiment in A Font About Which Editor Has Strong Opinions). If your thoughts stray to subjects like kerning before your composition is complete, I think you’re doing something wrong. If your goal in writing is to create clean, efficient prose, well, great, but personally I value those qualities in the consumer electronics I purchase, not the things I read.
I like to think of text as a convenient embodiment of speech, and the speech I most like to record aspires to being a witty, conversational and perhaps slightly tipsy soliloquy. Real human speech is not only full of asides, but is most effective when it’s delivered with a sense of timing. Em dashes are great for satisfying both of those requirements, largely because of the flexibility acknowledge by the article.