Why is cryptoanarchy irreversible?

It appears to be widely believed that cryptoanarchy is irreversible. Everybody believes that the race to deploy or forbid strong cryptography will define the outcome for a long time. I can't think of a reason why this should be so. If the wide use of strong cryptography results in widely unpopular activities such as sarin attacks and political assassinations, it would not be all that hard to forbid it, even after deployment. I am curious why many people believe this is not true. Peter Hendrickson ph@netcom.com