To me the argument is the equivalent of trying to stop eating fast food by asking a friend to come over everyday with fast food.
the problem isn't the fast-food, but the health of the fast food. proper comparison would be trying to stop eating fast food by only having healthy food around the house.
My interpretation of grandparent is that the app is probably another distraction in itself.
So, I'm not sure what the healthy food in your analogy is.
I guess I failed to provide a clear analogy for grandparent (assuming I interpreted them right).