As long as breaking laws where there are victims are still enforced. You shouldn't let a meth addict skip jail after they wrong someone. The biggest problem then becomes that "rehab" is simply a place where people who have no interest in cleaning up can get substitute drugs and new drug contacts at a very high monetary cost. Rehabs need to divide people who actually want to become clean, and then isolate those people in something like a camp or commune for long periods. Most states have no great programs outside of detox and group houses.