Microsoft allows Windows to run on anybody's platform that wishes to run it.
Apple, both with their OS and with their iPhone, only allows their OS to run on their own hardware.
But as most people never "get" -- is that Microsoft doesn't design and manufacture the phones. That's what Apple does. It's a "hardware" company that supplies the best software to make their "hardware work"...
Apple doesn't want crappy software on their hardware that they've made in such an excellent fashion. So, they have to make their own software since no one else has been able to do as good as Apple.
So, you've got a complaint -- it seems -- with the fact that no one else can make as good software as Apple needs on their fine products... LOL...
No, quite the contrary. I have a complaint with Apple suing other companies who build Apple compatible hardware and install legally obtained Mac OS.