Apple has not just created integrated HW/SW to sell as a product, with the AppStore they created a closed market within that product that only Apple controls.
They invite others to sell on that market, but made themselves gatekeeper and simultaneously a player there, controlling the rules of that market in its favor.
Market forces are unable to flow freely, to the point that it affects the "parent" market (in which the iPhone/iPad competes with others) as well as other markets (where other Hardware and Services are sold).
Their closed market reached a significant size now, so it should be reasonable to step in and ensure fair competition also there.
But thanks to those layers of abstraction, billions of dollar in lobbying and marketing, there is always room to argue that ensuring that free market is unjust, hinders innovation, restricts Apple from competing, etc.
They invite others to sell on that market, but made themselves gatekeeper and simultaneously a player there, controlling the rules of that market in its favor.
Market forces are unable to flow freely, to the point that it affects the "parent" market (in which the iPhone/iPad competes with others) as well as other markets (where other Hardware and Services are sold).
Their closed market reached a significant size now, so it should be reasonable to step in and ensure fair competition also there.
But thanks to those layers of abstraction, billions of dollar in lobbying and marketing, there is always room to argue that ensuring that free market is unjust, hinders innovation, restricts Apple from competing, etc.