> whereas for em-dash you need to do something extra

OPT+SHIFT+- on macOS. It's no more difficult to type than a lot of other punctuation/common symbols.

OK, that macOS. On Windows you had to remember the arcane Numpad combination (provided you had a numeric keyboard). That makes it uneven - the hyphen is just universal.

And on iOS it’s a long-press on the hyphen. It’s not inconvenient at all when you’re used to using them.