I actually think that rjc999 makes a lot of great points - but I think they're missing the bigger picture about Apple.
1- Comparing Apple to the vertical UNIX players of old (SGI, DEC, Sun, HP, etc) before they were commoditized by Linux/x86
None of these companies played in the consumer market. They built specialty hardware to solve specific scientific, business, visualization problems. Things like 3d hardware acceleration and 64 bit architectures were far beyond the practical needs of the home computer user. On the other hand, Apple's current competitors are often building more powerful hardware. There is a completely different dynamic taking place.
The razor-thin margins enjoyed by consumers in the PC era was due to the open specification of the PC architecture (allowing for commoditization) and one OS to rule it all. Make no mistake, plenty of margins were made in the PC era. By Microsoft.
2- Microeconomics 101, all products go to zero margin, eventually.
No. This is does not work for products that can be differentiated. How long have hand bags been around? Hundreds of years, with plenty of competition. Yet somehow there are $50,000 Hermès bags being sold today. How about something as simple as sugar water? Why do we continue to pay more for Coca-Cola compared to the no-name store brands?
Something else I should note is Apple's insane economies of scale. Consider the possibility that Apple can profitably manufacture and sell products equal or lower MSRP than competitors who are near 0% margin.
3- Developers moving to Android after "maxing out" iOS.
First of all, this implies that apps will generally come out first for iOS to test whether they'll be successful in the first place. This makes the iOS ecosystem a breeding ground for new, innovative apps.
I run an app business. I didn't bother with Android until, as you said, my app was proven to succeed on iOS. It took me over one year to reach that point.
4- Apple does not do R&D.
You're focusing a lot on purely science and hardware based R&D, of which Apple does plenty. Just look at their patent library for a hint of what they're doing in terms of semiconductors, display technologies, battery technologies, low-power consumption computing, etc.
What you're missing is the work and expertise Apple does in human computer interaction. This is Apple's trump card. Things like bouncing, simulated inertia scrolling seem so obvious after the fact, don't they? Thing is, they're not obvious at all before they were ever conceived. It takes a great deal of reseach in human psychology, capacitive multitouch research, and other topics of human computer interaction to come up with this stuff.
You can go ahead and dismiss this type of research as not "real science" but this stance will do you a great disservice in understanding why Apple went from near bankruptcy to becoming the largest market cap on the planet.