> The problem is, I don't recognise it has ever been a big thing.

This is not a problem. Or rather, it is not a problem in the way that I think you mean.

Em dashes do not need to be a big thing to be useful, which they are; they also do not need anyone's personal recognition to do their jobs.

The problem may, in fact, be that they used to be more of a niche punctuation mark that people were not very familiar with. Now that LLMs have fallen in love with them and throw them around like candy, if people have hardly ever seen them used in well-written text before, they might treat them alone as a much stronger signal for LLM generation than they should — which is precisely what is bringing em-dashes under fire these days, and hence results TFA.

So, yes, indeed, in some ways the problem is, that you don't recognise it has ever been a big thing.