I use em dashes a bunch in both informal communication and more formal writing. Mobile keyboards have em dashes, and I also have the compose key turned on on Linux.

Recent examples on HN, all 100% human-written:

https://news.ycombinator.com/item?id=43923622

https://news.ycombinator.com/item?id=43863882

For an example of more formal writing, this blog post of mine has 8 em-dashes across 6000 or so words: https://sunshowers.io/posts/monads-through-pbt/

I did ask Claude to review this post for clarity and flow, but not to generate any text.