Different thing. Using visible _ is a conscious choice.

Why?

It looks nice and has been a staple in hacker culture for decades, long before we had rich text and were just chatting on IRC.

Also it looks like _underlined_ text

It doesn't look nice at all to me. Real emphasis looks way nicer, that's its purpose. Now that we have rich text, why not utilize it?

I use both and will continue to do so. You're trying to lecture people who have been on HN for more than 10 years how "we" do stuff around here.

There's so much wrong with this reply I won't even bother trying to respond, I feel the negativity of this comment pour through my screen

underscores around italics and asterisk around strong/bold was an informal convention on bbs, irc and forums way before atx/markdown.

I'm talking about the HN markup, italics don't work here, only asterisks do

I meant underscores, just noticed

Who's "we?"

Everyone who uses italics on HN, which is a lot of us: https://news.ycombinator.com/formatdoc

Not to be a pedantic asshole, but those guidelines don't mention italicizing as emphasis, just that * causes italicizes. In fact the OP should probably say that they believe "HN users use italicization to emphasize," which again, who's "we?" _This_ style of emphasis, as others have mentioned, has been bouncing around IRC and whatnot forever.

Most of HN users