If you are selling phones, Traffic /= market share. There is good reason to believe that iPhone users use more traffic. They are the premium phone and their users spend more. Similarly, app installs are also not market share for the same reason.
There is even an argument that handset sales isn't market share, that the only real measure is to survey some people to see exactly what phones they own and use. That's the only way to include old phones that aren't used for much other than making calls.
Would traffic not be a good indicator of the parent's argument about that the iPhone is a replacement for a laptop? Based on the assumption most computer usage is internet-dependent now (a stretch, but not completely illogical), then a user with an Android device not connecting to the internet would probably need another device to do so?
There is even an argument that handset sales isn't market share, that the only real measure is to survey some people to see exactly what phones they own and use. That's the only way to include old phones that aren't used for much other than making calls.