Compatibility isn't an issue either. The analogy fails: I've got Kindle books that have a back page directing me to the publisher's website to buy more. Apple'

Compatibility isn't an issue either. The analogy fails: I've got Kindle books that have a back page directing me to the publisher's website to buy more. Apple's rules would prohibit it. Apple's restrictions on any content that suggests the consumer may access services by any means other than making an in-app purchase are not "par for the course", they are an unusual abuse of market power that directly misleads the consumer. I've also just re-read the App Store rules and noticed that for multi-platform services, it even contains a covenant outside of the walled garden: "your general communications about other purchasing methods must not discourage use of in-app purchase."