I used to use em dashes before they were cool. I actually learned about them when I emailed a guy who's a software engineer at Genius and also writes for The New Yorker and The Atlantic.
I asked him for tips on how to write well and he recommended that I read Steven Pinker's "The Sense of Style", which uses em dashes exhaustively, and explains when and why one should use them.
It also pains me that I can't use them anymore or else people will think an AI did the writing.