As a professional writer, I can confirm that my editors love to sprinkle em dahses excessively on my work.

Personally, I'm more prone to excessive semicolon usage, which seems to aggravate editors.

I'm not a professional writer except of software, but both there and in my non-professional writing, I'm a lot more likely to use semicolons than em-dashes.

As an unprofessional writer, I assume this is the result of wanting to make the text “punchier.”