Reddit doesn't have to: phones do. Just long-press the hyphen key and you get a popover to select an em dash, en dash or bullet.

It works the same way on a Mac (key repeat off) or by pressing option+shift+hyphen (key repeat on).

Long ago on Windows I learned alt+0150 on the numpad.

Yet now my hard-earned attention to detail attracts nothing but false accusations...

Ain't no one got the time for that. How do you even know these things without looking them up?

You spend a lot of time and money to study the humanities and have your work graded and corrected by picky professors.

Sure, but most people aren't humanities students. I feel the topic of conversation gets a bit lost in this thread at times.

If you like and use em dashes, you figure it out

I do. The point is that most people won't think about it, which is what we're talking about... There being a few outliers on a site called Hacker News who know the shortcuts for extended typography isn't in any way indicative of em dashes being in common use amongst phone users.