Quoting from the article,
"Apple attempts to justify these fees by arguing that the App Store is no different from a mall, where companies seeking to offer their products must pay rent to the owner of the mall (in this case, Apple). This argument conveniently ignores the fact that there is just a single mall when it comes to iOS and no possibility of a competing mall to rent space from. It is not illegal for Apple to own a mall and rent space, nor is it illegal for Apple to own the only mall. What is illegal, is exploiting the fact that it owns the only mall to charge excessively high pricing which harms competitors."
This is a recurring theme here on HN. The fundamental dilemma is whether or not it is a monopoly. The article is arguing that it is.