I'm starting to think that "computer-substitute" is precisely what smart phones have become, and that having a real computer you depend on might correlate with age, income or occupation in a way that phone ownership cuts across. It's pretty easy to finance a phone purchase through your carrier, especially compared to Apple's Barclay deal (unless this has changed a lot in the last few years.) I think a lot of people under thirty are borderline computer illiterate, but get by using their phone. For them, a bigger screen that's harder to type on is fine. For people with more money and computer literacy, it's just a matter of taste--but we're not the biggest slice of the pie.