Going to fall on its head. Apple isnt asking for fruits of their labour but charging from device abuse, management of store and general device health.
I don't think the fee is there to protect device health. There are plenty of free apps with no fees levied, so that point doesn't make sense.
I think it's fair to charge a fee for using the store as a paid app distribution channel. If Apple takes on the burden of risk, funds flow management, etc. it's fair to take a cut.
If Epic instead builds their own payment system, they shouldn't be charged for it or forced into using Apple's.
Apple could claim that they need to cover hosting costs or review costs. And I think there's an argument here, but it's not made, and it would raise additional questions around fairness.