Comment by BerislavLopac

And one thing that this article gets very wrong about Markdown: It was not designed to be a structured markup syntax of any sort. The syntax, in fact, was never actually designed as such.

Markdown originated as, basically, one guy's attempt to convert instances of unofficial text-formatting convention, commonly used in text-only communication such as emails and Usenet, into HTML that can be presented on the Web. In order to do that he had to enforce some standards, while still leaving some flexibility (which is why the top levels of headings have more than one forms; both were commonly used to designate the same thing).

It was only after companies like Stack Exchange and GitHub started using Markdown as, ironically, a markup language, that there were any attempts to enforce a standard. I clearly remember a whole online "war", for the lack of better term, arguing pros and cons of standardisation.