Interestingly, Apple is moving back towards the old console model. You now have a bespoke CPU/GPU platform from Apple running their own OS. I'd say we're already seeing the performance benefits of owning/designing/developing the whole stack.
[0]Yeah Apple says the GPU[1]is entirely their design at this point, but then quietly reached some kind of agreement with Imagination in the past year or so.
[1]Though considering how often GPU drivers need game specific updates and how fast GPUs change and improve, each GPU is almost like it’s own little bespoke platform.
The IBM PC was an exception and only because IBM couldn't prevent Compaq to carry on.