First, Epic is hardly a no name developer. But secondly a great deal of apps work like this both big and small. The limitation is you can’t make purchases though an app by say asking for credit card numbers or put purchase links to your website from the app.

There are well known and detailed App Store rules about this stuff, if you want details just look it up. For example all those 2 factor authentication app fits this model where it’s meaningless to download the app without a subscription.

Yeah because regular no-name developers like Epic can't read the damn rules. It's quite simple. If you don't want to get booted off the app store then follow the rules. The rules are very easy to follow.

If you offer a multi platform "content" app on iOS then users should always have the option to create a subscription account directly on their iOS device. It's perfectly fine to create an account on a different platform and use it in the iOS app but this should neither be required, nor be directly advertised in the app.

Seriously, don't make random stuff up. Amazon and Netflix don't receive preferential treatment. If you want to make your own streaming app on iOS you can do that today as long as you follow the rules.