It was just announced today at Apple's World Wide Developers Conference that the Apple App Stores had paid out $70 Billion to independent developers in sales of their apps and that $21 billion of that was paid out just this last year alone. That is a sign that your assertion that somehow there's more competition in the PC arena allows more people to develop things is not quite right. Apple's use standard hardware that works on standard PCs. There are SIXTEEN MILLION registered developers for Apple worldwide. I would be willing to bet that dwarfs the number of registered developers for Windows.
PCs still dominate the computer market no doubt. Even laptops.
Why? Cost.
Where Apple wins is in the cell phone and media player markets and their cell phones are tied to their music players.