Em People

"Don't you find it annoying—and you can tell me if you do, I won't be hurt—when a writer inserts a thought into the midst of another one that's not yet complete? Strunk and White—who must always be mentioned in articles such as this one—counsel against overusing the dash as well: 'Use a dash only when a more common mark of punctuation seems inadequate.' Who are we, we modern writers, to pass judgment—and with such shocking frequency—on these more simple forms of punctuation—the workmanlike comma, the stalwart colon, the taken-for-granted period?"

Noreen Malone in Slate rails against the use of the em dash.