The question is: has Reddit (or other Markdown users) actually studied Markdown's usability? Even a basic comparative study against a WYSIWYG equivalent?
It seems like "techy" people just kind of assume Markdown is great and easy and awesome without ever bothering to actually make any effort to question that assumption. That's really the part that bugs me most.
And the entire pitch of Markdown is that you can style your text the way you did back when you were using text-only stuff. Ok. So _this should be underlined, then_. And /this should be in italics, right?/ And naturally this is boldfaced. Oh wait. Markdown is ZERO FOR THREE.
(Strangely, Markdown doesn't even have underline. Go figure. It's not even remotely close to feature-parity with the WYSIWYG textboxes we were all using on the web in 2008.)