In a system with no rules how is there any comeback at all when someone behaves in a reckless way and hurts or kills an innocent other as the result of their selfishness? Which road users are those getting hurt or killed likely to be?
Yes, a complete absence of any formal principles would be a complete failure. What the-one-who-sounds-like-a-duck is implying is a scenario where the general principle of it is wrong to harm another human being (or maybe even just cause an accident) still applies. It needs to be thought of as an extension of the sort of traffic scheme where they take away all the road markings and allow pedestrains to mix with the motor vehicles. In other words, if the only guiding rule was 'drive safely' and everyone obeyed that, you might not need as many formal traffic regulations.