No, they created the possibility for the most valuable mobile software market in the world. Third-party developers were the ones that created it into the most valuable mobile software market in the world.
> by creating the iPhone
Creating the iPhone does not explain the source of the App Store's value, only that one is "tied" to the other. Which leads to my next point.
> You can describe this as anti-competitive, just keep in mind that you're assuming your own conclusion.
It's anti-competitive according to the law. The practice of selling a service (ie: commissions from App Store) as a mandatory addition to the purchase of a different product (ie: iPhone) is called tying. In the United States, most states have laws against tying, which are enforced by state governments. In addition, the U.S. Department of Justice enforces federal laws against tying through its Antitrust Division [1].
No, they literally created the market. The products sold in my supermarket don't create the supermarket either.
Whether what Apple does meets the legal definition of tying is an open question. I doubt it, clearly you're convinced, which is to say, you're assuming your own conclusion.
Also, because Apple created the most valuable mobile software market in the world, by creating the iPhone, continuing to release top-notch phones year after year, and by creating the App Store itself.
It remains true that iPhone users buy software at a rate that totally dwarfs Android. This could be traced to a number of reasons, but I wouldn't dismiss the App Store monopoly as one of them.
You can describe this as anti-competitive, just keep in mind that you're assuming your own conclusion. You could make the same argument for Apple's refusal to license their OSes for hardware they don't manufacture, I would be similarly unimpressed.
As a user, I would like a stress-free way to sideload apps which don't meet Apple's standards for inclusion on the App Store. Don't see why Apple would want to give away their competitive advantage by letting other stores sell software for their phones, but I could imagine them making side-loading less onerous, that would be nice.