Earlier quoted context omitted.
A shelf space analogy doesn't make sense. With a real shelf, there is scarcity. Only so many shelves can fit in the store, and only so many products on a shelf. The marginal cost of a virtual good is zero. Apple's ability to support apps is effectively infinite. There are over 1M apps in the App Store. This is not about "shelf space".
There is a kind of scarcity in abundance. When the marginal cost of shelf space approaches zero, another factor comes into play: time spent by the buyers. With too many shelves in the store, many products will never be bought, no matter how good they are.
There's already too many apps, so preventing "over choice" isn't their goal.