[belorn]

The argument for friction was lost the moment we got cheap access to home recordings, which at this point is any mobile phone that was produced in the last 20 years.

From all my history in computer security, conferences and just picking up trends in what criminals do, the most common channel for sharing CP should be, as an educated guess: Plain text email. A smartphone, a camera app and the email app that is already installed, as an educated guess, is the tool of choice for the wast majority of cases. For the remaining portion we got people who do not take most friction-less method, and here I doubt OnionShare will cause any change in the availability of CP.

A bit of a tell is that during the crypto wars there were officials that forbode that there would be an explosion of CP if free encryption was allowed. CP and nuclear proliferation was the standing bet between Eben Moglen and Phil Zimmermann on what the opposite side would first bring up, and I think its fair to say that neither issue occurred after Phil Zimmermann won.

Taking a perspective from behavior science, CP production and sharing is unlikely to be a rational decision where risk and reward is fairly balanced. As an example I would predict that increased jail sentences does not actually reduce the crime rate, nor would turning a very hard tool into only slightly hard to use tool. Effective measures would have to either address the emotional state of the person right before the crime, or implement catching mechanism in the tools with lowest friction like email and email replacements like chat.