@glyph (rant) em dash is a part of character sets I dislike, right along with curly quotes.

We have a dash. Want a longer one? Use two "--". Even longer "----". And those are right on the keyboard!

Quotes - who sees well enough to easily spot the difference between opening and closing curly/smart quotes? IMO, straight quotes and a back tick are more than sufficient. If I need to enclose text in something then we have these really clear ones already: [] {} ()

ASCII FTW here :-)