People are jumping to conclusions a bit fast over here, yes technically it's possible but this kind of behavior would be relatively easy to spot because the app would have to make direct connections to the website it wants to scrap.
Your calculator app for instance connecting to CNN.com ...
iOS have app privacy report where one can check what connections are made by app, how often, last one, etc.
Android by Google doesn't have such a useful feature of course, but you can run third party firewall like pcapdroid, which I recommend highly.
Macos (little snitch).
Windows (fort firewall).
Not everyone run these app obviously, only the most nerdy like myself but we're also the kind of people who would report on app using our device to make, what is in fact, a zombie or bot network.
I'm not saying it's necessarily false but imo it remains a theory until proven otherwise.