If through the app stores themselves then they’re essentially asking for discoverability, hosting, and distribution of their products for free.
At what point does a company deserve the right to compete with you on your own product? If Amazon continues to engulf online shopping can another company eventually sue to have their own store listings put on Amazon with no money going to Amazon?
To me these two situations aren’t that different. Apple and Google have each built hardware and software systems for their services. Other companies like Samsung have developed their own app stores that they distribute on their phones. If Epic wants to be a service provider then there are already charted pathways to doing so that don’t involve suing over service fees you already agreed to.
I get where you're coming from, I do -- but the answer to your question is somewhere around "when that company controls access to billions of eyeballs around the planet".
These companies have greater access to and control of people than any government. They are beyond review, beyond accountability, and beyond reach. They are dictatorships controlling access to billions of people, the kind of power that would make any dictator in history blush.
And I am not saying we should take from them all their power. They DID earn it, it's true and most of it is quite benign. But... giving them absolute power over who everyone in the world can do business with, just because they chose to buy that device (probably not knowing what the limitations would be)? For the sake of the future of the entire species I should think that this is not a situation we would consider ideal.
Both companies contribute to the open commons with open source software and sponsorships.
You could probably make a reasonable argument that Play Services are specifically designed to undermine the spirit of open source, but theoretically you could build an alternative, and use AOSP however you wish.
I don’t get what Epic wants exactly. Even with Android where they initially had users side load their apps they eventually gave up and put it on the Play Store after complaining that there’s too many warnings when users load third party APKs (how dare they include security warnings of un-reviewed apps!)
It seems to me that Epic expects Apple and Google to offer up an Epic App Store/Epic made games in their own App Stores free of charge, and conveniently ignore any developer terms they previously agreed to. Talk about entitlement.