I think it's delicious how nobody, absolutely nobody, wants _ to mean "emphasis," they want italics, and yet despite there being a markdown-to-HTML build step nobody has ever done what they were told they were supposed to do to circumvent the semantic issue and use <span class="italic"> instead of <em>.

It wouldn't even make sense for markdown if it were language-agnostic to output <em> when that's HTML-only.

I'm going to go to my grave repeating that <em> is just <i> version 2.