[WillPostForFood]

because both companies were deliberately undersizing their connections to Cogent

I think a clarification would be helpful here. Were they "deliberately undersizing" or were they refusing to to increase capacity to accommodate the surge in additional Netflix traffic without being paid?

This is how Cogent described it, “Comcast refused to continue to augment capacity at our interconnection points as it had done for years prior.”

via: https://qz.com/256586/the-inside-story-of-how-netflix-came-t...

Comcast claims: "Comcast executive vice president David Cohen said Comcast was forced to react when the flow of traffic with Cogent went from roughly equally to Cogent sending five times as much data as Comcast was sending back."

via: http://www.mercurynews.com/2014/05/08/cogent-ceo-comcast-pur...

[js2]

Cogent isn't sending traffic to Comcast willy nilly. Comcast customers are requesting the traffic. It's part of Comcast's cost of doing business to size their network to meet their own customer demand. Or at least, it should be, because most of Comcast's customers have no other choice of ISP, so normal market pressure doesn't work. So yes, this is (should be) a Comcast problem, not Cogent and not Netflix.

[WillPostForFood]

this is (should be) a Comcast problem

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.