Generally true, but to be clear, my generalized statement was not focused on "hard drugs" in which your input is certainly more true for. For instan" not. Black and white prohibition has proven to be unworkable while open freedom of any drug use has likewise proven to make society worse, thus is unwise."
That means we cannot use black and white drug use policy for all mental affecting A to Z drugs in all situations. Your input is certain true for harder drugs that society and this person quite agrees with. For other situations, especially given the vast numbers of physician prescribed pharmaceutical drugs, including those fighting depression, such is a gray area where will never be firm thresholds for much, It Depends... on individuals that vary greatly.
What I would add to the general discussion is highly unpopular with the psychology profession and most people. That is a return to some level of corporal punishments that is not by pain as was once practiced but rather by making at least some of those incarcerated, particularly lower level short term sentenced, more uncomfortable and unhappy of being locked up so, than many seem to be.
For instance, instead of a pleasant 70F degree indoor cell environment, a lack of air conditioning for temperature unless temperatures reached some more extreme levels live below 60F or above 80F. Instead of access to cigarettes, coffee, candy, television, take those away. Instead of a range of enjoyable food, very basic boring, though healthy food. Instead of peace and quiet, listening to some speaker teaching correct behaviors and why not doing whatever will result in consequences. Much more in that vein.
For drug users, if they are made uncomfortable every time they are arrested instead of just being released after a few days with a hand slap, if many would be in jail for a couple weeks in such conditions they would try to avoid repeating doing so.