A lack of net neutrality can be exploited without you (as a casual internet user) knowing it. It could be AT&T going to Netflix and telling them "Give me money or Netflix will be slower than Hulu". Netflix would pay, and you wouldn't know the difference.
Also, if you want a less hypothetical scenario: in 2012 and 2013, AT&T blocked FaceTime.
Also, if you want a less hypothetical scenario: in 2012 and 2013, AT&T blocked FaceTime.