ISPs face costs for peak usage / level of “playing with the numbers” yes, but economies of scale and exchange agreements reduce these costs significantly. Bandwidth caps not only have a weak financial justification but also run counter to net neutrality.
Zero-rating = skewing whole internet playing field, not just stifling small creators; subtly - or not so subtly - influences user behaviour, leading to a constrained experience. Users might feel financially pressured to use certain services, missing out on potentially superior or more diverse options, which goes against the original ethos of the open internet.
