I'm not sure this flies. Android is open source software, so there are many 'flavors' of Android supported by the vendors that forked the software. And each probably has their own app store along with the Play Store. My Samsung certainly did.That's a poor analogy since you conveniently leave out that there's plenty of retailers to do business with. In the mobile market, there's only 2: Android & iOs.
There are in fact many vendors to deal with. One is pretty successful compared to the rest, so the rest are going to try to pull it down.