Take the example back to computers. The independent builders can much more easily optimize their systems for speed, or capacity, stabiliy, efficiency, cost, etc., and can easily customize the mix of all these factors and others.
The problem with your example is that it works the exact opposite of how you said. Apple as a company
does have access to whatever components it wants to use. It's us, the end user, who does not (should we want to use OS X).
However, as far as optimizing our systems for speed, capacity, stability, efficiency, cost, etc., Apple is the one that worries about that. Not the consumer. OS X as a product is optimized to run on Apple-built hardware. The end user doesn't really have anything to optimize for themselves on their own hardware setup, unless they're building their own operating system. So Mac software
is optimized for Apple's hardware, and it's
because OS X is locked into Apple's hardware that makes it perform so well.
Now you may have meant something else. Perhaps you meant optimization, say, between a gamer who wants to optimize his rig for graphics and cpu performance vs. a photographer who wants to optimize his setup to have as much storage and memory as possible. You're right, that Apple's vertical integration model isn't quite as good when it comes to things like that. However, that's the cost of using OS X. Part of the reason it's such a stable, smooth operating system is due to the very fact that it's locked into a select group of hardware.
I agree that it's not always the best solution for some people, but when you look at the problem Windows has with drivers trying to support millions of combinations of hardware (and they've done a very admirable job, IMO), then I feel it's worth it. If I ever stopped feeling it was worth it, and decided I really needed to be able to choose my own hardware setup down to the chips, then I'd bite the bullet and build a computer to run a good Linux distro.
