If org more was as successful as markdown it would likely also have a lot of unstandardized additions.

One of the arguments of the article is that there is a fundamental difference: Markdown was created as a small subset of syntax elements. Therefore, there was a high demand on syntax extensions that were added in a chaotic fashion.

Orgdown already comes with more syntax elements that Markdown probably will ever get. So I do see a clear argument for the case that "unstandardized additions" to orgdown are less likely in addition to the fact that there aren't any.

Though at its current state, it wouldn't need that much more, because it can already do tons of stuff that markdown cannot even start dreaming about.