The example is deliberately contrived and hyperbolic. In real life, if there is reliable evidence that someone is murdering people, the police conduct an invest

The example is deliberately contrived and hyperbolic. In real life, if there is reliable evidence that someone is murdering people, the police conduct an investigation, we have a trial, and they go to jail. You know what we don't do? We don't go "Hey, I think Bob the pen-seller is a murderer. Nobody buy his pens so hopefully he runs out of money and can't afford to murder people anymore". We don't do that because it would be a really stupid and ineffective way of stopping murderers, and it's really stupid and ineffective for most other things too.