The authors argument that Markdown should be discarded because there are several competing implementations isn't valid.
For many years (even now), we have several competing implementations of HTML, yet the HTML document is the dominant presentational document format (and UI layout language). It hasn't done anything to hurt adoption.
The fact that Markdown does have a common subset of features, and that Markdown is widely interoperable with a vast amount of products is why it wins. As far as I can tell Org-Mode markup is used within Emacs and really nowhere else.
For many years (even now), we have several competing implementations of HTML, yet the HTML document is the dominant presentational document format (and UI layout language). It hasn't done anything to hurt adoption.
The fact that Markdown does have a common subset of features, and that Markdown is widely interoperable with a vast amount of products is why it wins. As far as I can tell Org-Mode markup is used within Emacs and really nowhere else.