Whenever I see an em dash (—), I suspect the entire text was written by an AI.
Also in the footer: "Everything on this website—emdash and all—is created by a human."
AI almost certainly picked it up mainly from typeset documents, like PDF papers.
It's also possible that some models have a tokenizing rule for recognizing faked-out em-dashes made of hyphens and turning them into real em-dash tokens.
On my own (long abandoned) blog, about 20% of (public) posts seem to contain an em dash: https://shreevatsa.wordpress.com/?s=%E2%80%94 (going by 4 pages of search results for the em dash vs 21 pages in total).
Three hyphens---it looks good! When I use three hyphens, it's like I dropped three fast rounds out of a magazine. It demands attention.
This article does not appear to be AI-written, but use of the emdash is undeniably correlated with AI writing. Your reasoning would only make sense if the emdash existed on keyboards. It's reasonable for even good writers to not know how or not care to do the extra keystrokes to type an emdash when they're just writing a blog post - that doesn't mean they have bad writing skills or don't understand grammar, as you have implied.
Incidentally, I turned this autocorrection off when people started associating em dashes with AI writing. I now leave them manual double dashes--even less correct than before, but at least people are more likely to read my writing.
en dash: https://www.compart.com/en/unicode/U+2013
em dash: https://www.compart.com/en/unicode/U+2014
Edit: Ah, Libreoffice does have a built-in autocorrect for em dash, but you have to type this:
:---:So ":---:" does work for the em dash? I thought something with fewer keystrokes work, too, at least I remember the em dash from less, but perhaps I just typed it so quickly I did not realize it was indeed ":---:".
That same critique should first be aimed at the topmost comment, which has the same problem plus the added guilt of originating (A) a false dichotomy and (B) the derogatory tone that naturally colors later replies.
> It's reasonable for even good writers to not know how or not care
The text is true, but in context there's an implied fallacy: If X is "reasonable", it does not follow that Not-X is unreasonable.
More than enough (reasonable) real humans do add em-dashes when they write. When it comes to a long-form blog post—like this one submitted to HN—it's even more likely than usual!
> the extra keystrokes
Such as alt + numpad 0150 on Windows, which has served me well when on that platform for... gosh, decades now.
Where do you think the training data came from?
It's the literary equivalent of thinking someone must be a "hacker" because they have a Bash terminal open.
No, it doesn't. But people are putting that out there, people are getting accused of using AI because they know how to use em dashes properly, and this is dumb.
I dunno, I feel like the base rate fallacy [0] could easily become a factor... Especially if we don't even have an idea what the false-positive or false-negative rates are yet, let alone true prevalence.
I'm pretty sure that all the comments about how it was "rarely seen" are because people weren't paying attention to them before in the way they do now.
In any case, to dismiss something as AI slap based solely on this one thing is both lazy and rude, and should be treated as such.
In general while reading blogs, Reddit, HN, youtube comments, X posts and so forth, I rarely never saw run-on sentences like that combined with em-dashes. Sure, they existed, but it was pretty uncommon up until about two years ago and now I see them all the time. So anecdotally, there is absolutely a shift in usage right around the time that LLM's took off. I wouldn't judge a professional article or book by its use of em-dashes, but I absolutely judge user generated text on the web.
Its not the only thing I judge on, though. Its just one of a number of red flags. Frequent uses of lists (of usually three items) and of bullet points too -- and run on sentences, not just the em-dashes. Yes, I did that on purpose.