Because it increases the chance that they'll need to resort to crime to survive. It's the same reason that the pervasive policies against hiring felons increase

Because it increases the chance that they'll need to resort to crime to survive. It's the same reason that the pervasive policies against hiring felons increase recidivism rate. Once they've paid their debt to society, we need to actually forgive them, or it's much harder for them to rehabilitate.