"Comcast is essentially deploying against their own customers techniques more typically used by malicious hackers (this is doubtless how Comcast would characterize other parties that forged traffic to make it appear that it came from Comcast). In this sense Comcast is behaving worse than if they dropped a proportion of packets under congested circumstances in order to throttle bandwidth usage, or even if they blocked certain ports on their network.
[...]
"Comcast's conduct also threatens innovation by undermining the end-to-end principle. The Internet has enabled a cascade of innovations precisely because any programmer -- whether employed by a huge corporation, a startup, or tinkering at home for fun -- has been able to create new protocols and applications that operate over TCP/IP, without having to obtain permission from anyone. Comcast's recent moves threaten to create a situation in which innovators may need to obtain permission and assistance from an ISP in order to guarantee that their protocols will operate correctly. By arbitrarily using RST packets in a manner at odds with TCP/IP standards, Comcast threatens to Balkanize the open standards that are the foundation of the Internet."
-- Peter Eckersley, Fred von Lohmann and Seth Schoen, "Packet Forgery By ISPs: A Report on the Comcast Affair", Electronic Frontier Foundation, November 2007