Fortnite has been kicked from mobile app stores over the ‘App Store tax’, the 30% cut that Google and Apple charge for in-app purchases.

Apple needs Fortnite to keep the iPhone attractive, but it also needs its revenue cut, as services have become a key part of its growth story to investors.

Apple can no longer set its ecosystem rules without regard for partners, as apps like Fortnite, Amazon and WeChat are so central to the utility of a smartphone.

Apple’s developer conference coincided with a period of unprecedented tension with its developer community, parts of which are chafing under Apple’s rules for the iPhone App Store.

These rules let Apple extract a large portion of the value of the App Store. This revenue is more important than ever to Apple’s growth story, so it has been applying its rules more strictly.

Apple is constrained here by the need to deliver the best product possible to its users, and by the possibility of regulatory intervention.