even if that's true (it is and it isn't, but the pedantry isn't important), what you're saying is effectively is that a duopoly over mobile devices is the same as a monopoly over the internet.

that's patently untrue. it's untrue in the simplistic sense that you can access the internet with non-mobile technology, and its even untrue in the slightly less simplistic sense that an organization can provides its online presence as a website (gasp!) so as to avoid the need to have an app available on corporately-controlled stores.