The reasons why Markdown is popular are I think very similar to why HTML is popular. In its first years, it was loosely specced, very liberal in what it accepte

The reasons why Markdown is popular are I think very similar to why HTML is popular. In its first years, it was loosely specced, very liberal in what it accepted and was parsed differently by different implementations (browsers). When this actually became a real problem, HTML5 came out to spec it much more rigorously. RST in that picture is XHTML. Rigorous spec, but very picky with the input. Typo? Your whole document won't render. I've been bitten by XHTML and I've been bitten by RST. The experiences are very similar. I agree with the need for a more rigorous spec but like with HTML it still needs to be liberal with its input. So that's what we need, and I just hope it doesn't take years to come into existence. An HTML5 for markdown. And we shall call it MD5!