People who don't like socialism like to talk about how it values the society above the individual. This is true some extent, and especially here: As other pointed out, this is beneficial to society - I'm sure you'll agree the main problem that drugs cause society is crime, which is often related to the fact that people who are addicted need money to buy their drugs. This money also gives power to the criminals who sell the drugs.
However, it is not very beneficial to the individual. It does keep him out of trouble, and lets him keep his money and maybe have a chance to put his life in order. However, it doesn't solve the underlying problem of the addiction. And that's why this doesn't sit well with me: it represents both a surrender - giving up hope of ever curinging a person of their addiction - and a cold calculation of the values of lives - letting a person continue their self-destructive behaviour while protecting only the society around them.