What is the key combo to make an emdash?
On a phone keyboard, sure, it's as hard as an accent sign (á, for example), difficult but not twrrible. But on a keyboard? Yeah, no one is typing in Alt combos when literally any other construction will do.
For me, --- gets converted to an em-dash (—) while typing, if I have my input method (ELatin) enabled. I'm so used to typing in while working in LaTeX I can easily slip it in elsewhere.
On macOS (and iPadOS if used with certain external keyboards), it has long been `Option` + `Shift` + `-`. Desktop publishing folks memorized this, and other, typographically helpful key combos many years ago.