They believe that all useful Internet communication is centralized: for two parties to communicate, a third party (GMail, AIM, Facebook, HN, Twitter, etc) must relay the messages. But this isn't even true for email! Most companies run their own local servers. There is no central broker to tap - it's just P2P communications. Hell, if you and I open our college number theory books, implement RSA, and share port numbers and IP addresses, the law hasn't considered us. But we don't need to do that - there are plenty of expert-reviewed P2P technologies that allow for secure communication. It gets worse: I could use a VPN, and pipe my results through TOR, and use secure proxies. People just use centralized services because they're nice.
In this case, the government is asking citizens to sacrifice their liberty (and companies to sacrifice their valuable time) for something that can only be ensured by direct access to a suspect's computer, without providing any solid evidence that our safety has been threatened. FUD at its finest.