I guess part of the advantage of being an extremely long-winded writer who makes lots of typos is that people know that what I'm writing is probably written by a human.
Though maybe people will start supplying context like "no em dashes, and occasionally misspell a word or two", and soon you won't even be able to tell that.
Typos and EM-dashes are not just obvious. They are avoidable. Here's the kicker: Even if you remove those, other AI smells don't just exist. They are obvious.