A sad developer treatment, and a sorry-ass state for a platform, but not related to antitrust law, much less a "textbook antitrust case". For starters, Apple is not a monopoly. You are not a monopoly on your own platform, especially if that platform doesn't even have the majority of the relevant market. A company makes a platform or product so that they dictate the terms and if it's a marketplace, what and how it acc…
In what sense is it not a monopoly?
Walmart doesn't have a monopoly on toasters because you can go across the street and buy a toaster at Target or order one from Amazon, and it plugs into the same power outlet and works with the same bread and may even be the exact same model of toaster. If you want to sell your toasters and Walmart won't give you a good price for them, you can sell them to the same set of customers through dozens of other channels.
If you want to install an app on your iPhone, you cannot get it from Google Play. If you are an app developer who wants to reach your entire customer base, you cannot choose between Google and Apple, you must use both. Because the customer with one type of device cannot use the other store.
> You are not a monopoly on your own platform
It certainly isn't inherently necessary for you to be. For example, Microsoft has no existing monopoly on app distribution to customers with Windows. But if there is no on else who can distribute apps to that distinct identifiable set of customers, you have a monopoly on app distribution to those customers, because "monopoly" means no one but you can do that. And no one but you can do that.