The issue is that while they are trying to break the addiction they often relapse and because drugs are expensive and also not conducive to holding a job there is a non-negligible percent of people that would continue to break into cars and steal things to pay for their habits. If they aren't hurting anyone ok fine let them go the rehab route first, but if they demonstrate they are a danger to society then they need to be separated until they cure their addiction. I think we should also reduce the sentencing for drug crimes as often they are overly punative.