Point well taken:

Today's Internet is wildly skewed in favor of rich, English-speaking companies and users. Onlyfive percent of the world's population speaks English as a first language, but 55 percent of webpages are in English.

The countries without Internet access are exclusively the poorer ones—the "developing world." That means our Internet device is going to need to be as cheap as possible so that people can actually afford it, and the cheapest Internet-enabled device we can make is the smartphone. Its small size and relatively lightweight OSes are both qualities that lead to a low bill of materials, provided you aren't trying to make it powerful enough to double as a game console.