Something changed in the last couple of months if not years now. Open Slack, open a Notion page, scroll LinkedIn for thirty seconds, and there it is: a long dash sitting in the middle of a sentence, doing a job a comma or a period used to do just fine. It shows up so often now that it isn’t really a stylistic choice anymore, it’s a tell.
A character almost nobody typed
The mark is the em dash. It’s called that because its width was traditionally set to one em, the width of the letter M in a given typeface, which also makes it roughly twice as wide as its shorter cousin, the en dash. It isn’t new. Printers were already using something close to it in English drama as far back as 1588, when Maurice Kyffin’s translation of Terence’s Andria used a run of hyphens to mark broken, interrupted speech. A few decades later, other translations of the same play leaned on the same trick dozens of times. Eventually the expensive folio editions settled on a single unified rule instead of a chain of hyphens, mostly because it looked better on the page.
From there it settled comfortably into professionally edited prose for a very long time: novels, essays, journalism, the Chicago Manual of Style, the AP Stylebook. American convention kept it unspaced; British and Canadian style guides often preferred a spaced en dash instead. Either way, it belonged to people whose job was to set type or edit copy, not to everyday writers dashing off a message.
And here’s the part that actually matters for the rest of this article: almost nobody could type it. A standard keyboard gives you a hyphen and nothing else. Getting a real em dash meant Option+Shift+Hyphen on a Mac, an alt code on Windows, or the old Courier workaround of stringing two hyphens together, because monospaced typewriter fonts never had a dedicated glyph for it. If you wanted the effect, you either learned the shortcut, let autocorrect handle the double hyphen, or gave up and used a comma. In everyday, unedited human writing, the em dash stayed rare mostly because it was a small pain to produce.
Why the models can’t stop using it
Large language models learned to write from the opposite end of that spectrum. Books, academic papers, edited journalism: text where the em dash shows up constantly, because it costs nothing to produce with a keyboard shortcut and carries none of the friction that keeps casual writers away from it. That training diet taught the model that this is what careful, “considered” writing looks like, so it reaches for the same device sentence after sentence, whether or not the content actually calls for a pause or an aside.
What it doesn’t have is what a human editor has: a sense of their own tics. A writer eventually notices they lean on a phrase too much and cuts it. A model generates one token at a time, with no memory of how many times it already used the same trick three paragraphs up. Nobody trained it to notice its own habits, so nothing ever tells it to stop.
Why it reads as a fingerprint
Take those two things together and the em dash stops being neutral punctuation. A person typing quickly in a DM doesn’t go out of their way to produce a character that needs a special key combination. They reach for a hyphen, a comma, or nothing at all. A message full of unspaced dashes doing the exact same rhetorical move over and over isn’t how people type under normal conditions. It looks exactly like what it is: text a model produced, pasted in unchanged.
Why that’s a problem
Start with trust. A Slack DM or a Notion page written entirely in that voice reads like nobody actually stood behind it. If the sender didn’t write it themselves, did they even think it through, or did they just ask a model what to say and forward the reply? The message stops being proof of someone’s judgment and starts being proof that the judgment got outsourced.
Writing something yourself, even a couple of sentences, is a small act of care toward whoever’s reading it. Pasting model output wholesale, dashes and all, without even a pass to make it sound like you, tells the reader you didn’t think the message was worth that much of your time. People notice that, even when they can’t quite say why.
And underneath both of those, slower and easier to miss day to day, sits homogenization. When enough people on a team lean on the same tool for the same tone, every DM, every project update, every Notion doc starts sounding like it came from the same person, and that person is nobody in particular. A team’s culture lives partly in how people actually talk to each other: the shortcuts, the register, the little quirks of individual voice. Flatten all of that into one polished, hedged, dash-heavy cadence, and you lose something that was quietly doing real work, even if nobody would have called it “culture” at the time.
Read what comes back before it goes anywhere, and rewrite the parts that don’t sound like you. A tool that ghostwrites your Slack messages and your Notion pages is, quietly, a tool writing your reputation too. Worth noticing, before it just becomes the default.