Geez, by that logic, we shouldn't prosecute murderers. No, you file suit to a) punish him for breaking the law; b) keep him from doing it again; and c) prevent others from doing it too.
How typically Liberal of you to try and twist things around. We're not talking of "prosecuting" criminals. This is a civil action, not criminal. Your attempt to equate this to a criminal action destroys any credibility you think you have.