Markets work because lots of different people get to make purchase choices. Their choices become information that feeds into the competitive process. If there's demand for a product, the price offered for it should increase (the manufacturer should be able to carve out larger profits). That should attract competitors, and increase supply, and the competition should help create products that are both better designed and lower priced.
When Apple prevents access to the market, it stops this process taking place. If there's no price signal, there's less incentive for people to compete; the product's niche hasn't been validated.
But you're right, this market is hierarchical, and at a higher level, Apple is just a part of the bigger market. In that market, I choose Android in large part because of how Apple controls their sub-market.
