where is the em-dash key on your keyboard? Yes, I know you can use a shortcut. 99.9% of people don't.
Level 4 modifier + some key with my custom setup. On Linux in my locale and with an AltGr key you can use Shift+AltGr+hyphen.
You thought I wouldn’t have a reply to that?
Many editing tools support double or triple hyphen that convert automatically to em dashes. On Android it's trivial to write an em dash (easier than say the percent symbol).
I even have a plug-in that converts some hyphens to em dashes on my blog.
Rendering judgment on someone who published something on their own site without knowing their stack reflects more on you than him.