Look at any time period, any medium, and the most creative work is always going against the grain.You are indulging in a circular definition in which most creative stands in for best or most worthy art, which of course depends on the premise which you set up in the first place, and which is a peculiarly 20C view of art. Only with the break down of the patron system and in quest of a new definition of art and a new place in the world did artists turn to the idea of being a creative force challenging the status quo (economic and artistic).
I don't think Michelangelo for example would have recognised your definition of his art as only meaningful in as much as it breaks the rules. His art was almost all in service of the church, which was the dominant political and economic force of the time. You can try to rewrite the history of art as a history of innovation and rebellion, but why bother? Why not understand it in its totality, which is certainly not as an instrument of rebellion, or even as a force for change - for much of the history of art change was gradual and consensual over decades and centuries, and nothing to do with challenging authority, quite the reverse, it was usually in the service of authority, used as propaganda, teaching materials and social proof. Art was a useful craft for most of its history.
Great art can include rebellion, but it is not confined to it, and frankly I think you're defending a pithy but inaccurate slogan which falls far short of capturing the full role of art in our society.
