[netsharc]

Mobile app means access (due to broken permission systems) to a user's contact, location, mic and camera. Also, captive web browser (user clicks a web link and that web page gets shown inside the app, instead of on the phone's own browser) means the app can track what sites you visit and for how long ("Dear buzzfeed.com, would you like to buy our stats for visits to your website?").

[orbitur]

"broken permission systems" is just Android. iOS could offer more fine-grained options, but it's solid.