Drug dealers, Pedophiles and terrorist all use email, cell phones, public roads and snail-mail to organize, and conduct, their illegal activities. Is it a realistic reaction to consider shutting each of these down every time there is a new conviction?
No Snail-mail on Sunday is unrelated to people using it for illegal purposes.
Public roads being shut down, even for crime fighting efforts, is not the same as 'shutting down' Facebook or Twitter for your citizens. The proper analogy would be 'Someone was hit by a drunk driver and we believe more drunk drivers will illegally use the road so no one is allowed to drive on any roads for any reason.'