Since when, and what's your authority for such a statement?
Retribution/punishment is one of the foundations of the justice system's basic reasons for incarceration, along with protecting the public from future crimes and along with rehabilitation.
It's a legitimate stand-alone basis for punishment and incarceration, in fact it's the moral basis for incarceration, whereas protecting the public is the practical basis.
That is true in theory. But everyone knows what cgk means and I suspect you do also.
Letting these freaks out with light terms or no terms or even after they have served their terms when they commit these crimes over and again is not protecting the public, is it?