This is the legal ground for preventing Apple from enforcing the agreement. Some commenters are wondering whether contractual law allows that. And I'm saying it does, if Epic can prove that some elements of the contract are illegal. I have argued elsewhere for the illegality of the contract.
Let me repeat my argument:
1. A platform for developers sell products to users is a service.
2. An operating system on which users can run apps is a
service product.
3. These two are distinct. They can be offered by different entities. And even if they are provided by the same entity, they are functionally separable.
4. "An unlawful monopoly exists when one firm controls the market for a product or service, and it has obtained that market power, not because its product or service is superior to others, but by suppressing competition with anticompetitive conduct." (
https://www.justice.gov/atr/antitrust-laws-and-you)
5. Therefore, Apple's App Store has an unlawful monopoly over the first service.