Yes, zero-rating is a direct affront to net neutrality: https://www.eff.org/deeplinks/2016/02/zero-rating-what-it-is...
But I don't think that we're going to see many successes in net neutrality at the federal level anytime soon - the fight really has to be carried out at the state level.
Tmobile, Verizon, AT&T and Sprint uses 0 rating.
That's the entirety of the American wireless infrastructure.
It is literally impossible to use 4g wireless communication in America without patronizing directly or indirectly a 0 rating neutrality violator.