The Apple/DaringFireball fanatics have gone, and the web programmers learned how to really program because they had node as an option, but we've been stuck with this ugly, limited non-standardized format.
I'm an AsciiDoc partisan. I think we should just standardize a subset of AsciiDoc that does everything that markdown does and let people just implement that subset if they want. AsciiDoc gets a bit hairy when you get into the weeds, but if there were some sort of graduated standard that layered on features, you could learn as slowly as you wanted, and only by necessity. AsciiDoc gives you what you need as a base to automate typesetting basically everthing, as far as semantics go.
edit: I have to admit that I do not like AsciiDoctor, but it's just because I hate introducing Ruby dependencies. The people behind AsciiDoctor seem really great.