I think the article explained that reasonably well. One example is that they also make their own apps, so you potentially have to pay your competitor 30% of your income which is more than your own margins. And then they surface their own app and hide your's. Cannot compete against that.
My issue with the article is that despite acknowledging that Android market share overall they are acting as if Apple is the only game in time. Maybe my thought process is just overly simplistic and I'm missing something because every time the app store gets brought up my general feeling is just don't use Apple. If enough developers abandon the platform they will be forced to change.
I'm curious how often this has actually occurred in the App Store? I can't think of too many apps that Apple has released that have many competitors. Sure, there are the built in apps (which you can remove) but I certainly haven't seen any lack of To Do or weather apps on the App Store.
It's an issue for Spotify vs Apple Music for instance. Apple wants a cut of Spotify's fee, and also had APIs for Apple Watch etc only they themselves could use.
