Private companies can and do share (heavily scrubbed) electronic signature information, but must go through contortions to do so, and incur huge legal costs to do it. As a result, only the largest companies participate in these efforts.
Because the USG is more or less enjoined from participating in clearinghouses with private companies, information sharing networks are handshake affairs that are often unknown to anyone outside tier-3 network engineering. Other private IT security product companies run de facto clearinghouses, but only for their customers.
As a result, when your startup gets DDoS'd and you call your ISP for help, they generally can't do shit to help you. It may annoy you to know that if your connectivity provider is large, there is a group in there that could offramp your traffic to internal "scrubbing centers" to peel off DDOS traffic. But because high-end DDoS protection at ISPs is done sub rosa, startups have a very hard time finding these people.
There is an actual problem with online security attacks right now, and hysteria over any USG intervention with the Internet at all is helping perpetuate it. And all it appears to take to fuel that hysteria is statements like "think of the overreach that will happen once a law hits the books".
