There is always a point at which you don't control the stack, that's been the case for decades now. Just look at the CPU and how you can't change the code that interprets microcode (I think I'm using that term right) or, even more insidious, the Intel ME. Yes, Apple has moved their control up the stack but some people pretend the world was an open source utopia before Apple created the iPhone. As someone who has to provide tech support to my family/friends I can tell you I couldn't be happier that they can't screw up their phones like they do their computers.