In your apparently ideal scenario, if the would-be victim doesn't make a formal complaint with the authorities (which involves making a case go public, spending money on lawyers, going to court several times, explaining the details of the situation to a jury in front of you that may or may not sway your way, if the jury doesn't sway your way then your life may be ruined, etc.), then the would-be crime will always go not only unpunished but also easily swept under the rug.
Isn't this exactly what the #metoo movement stands against?
Sure, armchair judgments are a terrible method, but isn't your scenario even worse?