That's an arbitrary assessment. It is a problem for both sides. Netflix was paying Cogent for bandwidth. Cogent was taking advantage of a peering agreement (peer ~ equal) that was then thrown way out of balance. Netflix switched from paying Cogent to paying Comcast - both sides had obligations to pay for bandwidth from the beginning.
That's an arbitrary assessment. It is a problem for both sides. Netflix was paying Cogent for bandwidth. Cogent was taking advantage of a peering agreement (peer ~ equal) that was then thrown way out of balance. Netflix switched from paying Cogent to paying Comcast - both sides had obligations to pay for bandwidth from the beginning.