But in a case like Netflix the whole ecosystem that Apple/Google have built aren’t providing any value for Netflix. No one discovers Netflix through the App Store. The iPhone is just one more device that Netflix will try to support because customers want to be able to access Netflix on as many different types of devices as possible. This is way different than for example an indie dev building a game that is best enjoyed on a mobile device.
Netflix can choose to disable subscribing to it's services through the app. Maybe no one "discovers" netflix through an iOS device, but apparently a lot are starting their subscription through it.