That is certainly one very primary role, to prevent harm to good people.
The problem is that by simply taking the stance that anyone who does harm shall be cast into the sea in itself does harm and therefore does not cause your intended goal.
If a government for example forces against their will someone to be a murderer for 4 years (what we call drafting someone), and that person winds up being a violent person due to their traumas inflicted upon them, and then the consequence of that violence is for them to be cast into the sea.. then we have not prevented good people from harm, we have in fact infliced harm on a good person.
So unfortunately this mentally is contradictory to its own purpose when applied universally.