It's true that trade of physical items in the end is just a social convention. But the current legal status of bubblebum theft is based on depriving someone els

It's true that trade of physical items in the end is just a social convention. But the current legal status of bubblebum theft is based on depriving someone else of their physical property. It is not at all related to the shoplifter getting to unjustly enjoy the bubblegum. Re both having a nonzero marginal cost: There is no consistent criminalization of wasting other people's time or money as they're trying to engage you commercially. Of course there's a separate system under which we evaluate if something is unlawful remote access of other people's computers, and I suppose that could be perverted to criminalize ad-blocking, but the sense of justice of the average citizen does not call for it.