Dash it all

 There's some kind of mild uproar online over the use of the em dash, which is supposedly prevalent in AI texts, and it has produced inevitable crank commentary on punctuation. I can't speak to to AI prose, because my time is occupied dealing with substandard human intelligence prose, but I do know about dashes. 

The mnemonic is that hyphens join and dashes separate. That is, hyphens join compounds while dashes separate syntactic elements, representing a break in continuity. Good judgment suggests that the em dash,* like the exclamation point, should be used with restraint, to avoid cheapening the effect. 

The tell about overuse of dashes is in U.S. journalism. Reporters are dash-happy, and the reason, oddly, is the mechanics of the Associated Press. 

Attend. Journalists do not use dashes to express a break in continuity; they use them to set off parenthetical information. They cannot use parentheses for this purpose, because they use parentheses instead of square brackets to indicate interpolated explanatory material. They do not use square brackets because AP can't transmit them to all its members (which is also why AP does not transmit diacritical marks).  

See? I just made a parenthetical addition to the previous sentence, not a break in what I was saying. 

* Unless you are involved in book publishing, you probably have little occasion to deal with the en dash, which joins some, but not all, compounds.