My point is that saying iPhone users are by default AT&T users rests on the assumption that people have stuck with the same decisions they made about mobile net

My point is that saying iPhone users are by default AT&T users rests on the assumption that people have stuck with the same decisions they made about mobile network and phone operating system that they made over a decade ago. That isn't even factoring in the growth of the market overall and the people who have bought their first smartphone within the last decade.