Apple's guidelines already cover their bases to prevent such a loophole.
The first clause of their Payments[1] guidelines explicitly states you're to use in-app purchases to unlock features and functionality within your app, while also forbidding you from linking to or directing users to any alternative purchasing mechanisms.
They then make limited exemptions for "reader apps"[2] to allow users to consume content they've previously purchased, and explicitly list which categories of content they consider allowable for this exemption. Games not being one of them. They also make an exemption for multi-platform services which isn't as restrictive as the reader app clause, but only if you also abide by the first clause of making it available as an in-app purchase as well (and not direct people to alternatives for purchase).
So this works for Amazon's Kindle app, but wouldn't for a gaming service. And even the way Amazon handles Kindle listings[3] in their main app is toeing the line of what Apple allows, and smaller companies would have a hard time pulling off.
And just for good measure, they also pretty much spell out exactly what you described in the first bullet under the Unacceptable clause[4]
[3] "This app does not support purchasing. Books purchased from Amazon are available to read in the Kindle app" is what they put on the listing page. It's not a direct call to action so isn't strictly against the guidelines, but such a thinly veiled insinuation is something few other companies would be able to get passed app review.
The first clause of their Payments[1] guidelines explicitly states you're to use in-app purchases to unlock features and functionality within your app, while also forbidding you from linking to or directing users to any alternative purchasing mechanisms.
They then make limited exemptions for "reader apps"[2] to allow users to consume content they've previously purchased, and explicitly list which categories of content they consider allowable for this exemption. Games not being one of them. They also make an exemption for multi-platform services which isn't as restrictive as the reader app clause, but only if you also abide by the first clause of making it available as an in-app purchase as well (and not direct people to alternatives for purchase).
So this works for Amazon's Kindle app, but wouldn't for a gaming service. And even the way Amazon handles Kindle listings[3] in their main app is toeing the line of what Apple allows, and smaller companies would have a hard time pulling off.
And just for good measure, they also pretty much spell out exactly what you described in the first bullet under the Unacceptable clause[4]
[1] https://developer.apple.com/app-store/review/guidelines/#pay...
[2] https://developer.apple.com/app-store/review/guidelines/#rea...
[3] "This app does not support purchasing. Books purchased from Amazon are available to read in the Kindle app" is what they put on the listing page. It's not a direct call to action so isn't strictly against the guidelines, but such a thinly veiled insinuation is something few other companies would be able to get passed app review.
[4] https://developer.apple.com/app-store/review/guidelines/#una...