No? Apple charges a fee on every app sale. Where do you think the app makers pay that walled garden tax?
Buying apps is hardly "all activity on a phone". It's completely inconsequential to my spend since summer of 2008, when I began using Apple products. Maybe a couple hundred dollars in total app store purchases? It would make no sense for me to base a decision about devices I use day and night over that small amount of money (30% of a couple hundred dollars).
Never spent money on an app on my phone.