> Depending on the context, the em dash can take the place of commas, parentheses, or colons—in each case to slightly different effect.” The “slightly different” part is, to me, the em dash’s appeal summarized.

For me, it's of the opposite. It's like using `auto` too universally in C++: sometimes it's helpful to know the type you actually intend. Although I cede that the overuse in the article is more likely because it's discussing it and making a whimsical point. :)