I'm no ad expert, but I have to think if Apple starts advertising my app, more people are seeing my app.That assumes that Apple is advertising to a significantly different population of users than the developers are, which seems unlikely. Otherwise, I don't get how Apple's ads would be convincing people that wouldn't be convinces by ads from the dev? It's not like they can use wildly different messaging or art or anything without dev approval and not open themselves up to a lawsuit.