It seems reasonable to assume that people would not buy Apple products if they were too difficult to use.
It seems reasonable to assume people do not buy them for ease of use. Other competing systems are also easy to use. It seems reasonable to assume they buy them because they "look cool", much more so than any competing product.
It seems reasonable to assume the initial attraction to Apple products is the hardware design, not the software.
But none of this can be proved or disproved unless Apple were to unbundle the two and hackers were allowed to write software to run on the bare metal, not necessarily on top of Apple's development platform.
If Apple is afraid to try this then it shows they have something to fear. It shows they feel the need to exercise command and control over how users use Apple computers.
Apparently Apple's hardware design patents are not enough.