This discussion is about Epic charging for in-app things outside of Apple's control. So apple can't use the argument that they have costs (support, payment) for those transactions.
If I buy a hat in the Epic store (and pay to epic) I don’t see why it would be very different.
Should it matter if I make the purchase in Safari or in another app?
Also: let’s forget the apps for a while. Assume I buy a navigation app for $10 on the App Store and then I visit a website and purchase gps maps for 3 countries to use in the app, for $100 each. Apple isn’t involved in that transaction. Should they claim a cut of the $300 because I can use the maps in the app?
Epic would like to proccess these themselves. They dont want apple to turn on their economic output. When you charge money for the work others do -- that's like communism.