Apple has allowed cloud gaming apps on the App Store since earlier this year, but cloud gaming services still haven't bothered making iOS apps. Microsoft recently explained why, telling UK regulators that it didn't bring Xbox Cloud Gaming to Apple's App Store because the rules are still too restrictive.
The UK's Competition and Markets Authority is investigating mobile browsers and cloud gaming, and put out a call for comments. Microsoft responded in late July (via The Verge) and said [PDF] that while cloud gaming apps are technically allowed, there are still multiple rules that cloud gaming apps can't comply with for "technical and economic reasons."
Microsoft's chief complaint is that the App Store rules require subscriptions and features to be made available on iOS devices with in-app purchase, which is "not feasible." A consumption-only situation where content is purchased on another platform and played on iOS is not allowed for cloud gaming apps.
Apple's 30 percent commission fee "makes it impossible" for Microsoft to monetize its cloud gaming service, and it is neither "economically sustainable nor justifiable."