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.
Who knows how much of the comments on any website are written by humans now; yeah there are plenty of tells so it can be obvious, but that might only be for the exceptionally bad posts.
Checked LinkedIn and found four posts in a row that had "here's the kicker".
LinkedIn has always been a place full of low-effort posts for people trying to self-promote, so I guess it makes sense to have a robot actually do the thinking for something that is and always has been inherently mindless.