It's pretty ludicrous that this is an accepted notion. App stores are anticompetitve practices at their finest. (Especially Apple's situation, where they're competing with offerings from companies like Amazon, and slapping them with 30% cuts that price them out.)

We have two smartphone platforms that have basically full control over third party software. A company or individual that produces application layer software can hardly just come out with their own OS (and expect any amount of mass adoption). It's preposterous.

This goes even deeper than the issues with the Microsoft investigations of the 90s, but the only difference is a lack of monopoly-level marketshare. Which is hardly a sufficient excuse to permit this kind of behavior.