I don't think there's any hard cut-off where you can say something is art or not art. But even the most formulaic genre fiction gives more freedom to the author

I don't think there's any hard cut-off where you can say something is art or not art. But even the most formulaic genre fiction gives more freedom to the author in how they can arrange their words. English language doesn't have a formal grammar and rules are more like suggestions. But if mathematics breaks the commonly accepted rules then it's just plain wrong.