Some people who were sousing on alcohol would go to drugs.
Others already on drugs would keep it up.
Interdiction catches something like 10% of all pot... this is pitiful.
The answer lies in a different dimension. It lies in the direction of inviting and allowing God back into our lives. The reason far fewer people wanted to habitually poison themselves with non medically needed drugs in olden days, is because they welcomed the idea with all the relish of welcoming a visit from Satan. Now the attitude is more like “Cool! Satan!” And nobody is going to be able to do anything about that other than God, and God won’t until God is invited.
That recreational drugs have become much more common than in the past is indisputable.
I suspect part of the reason is that many, notably meth, just weren't available. Of course, they weren't available largely because there was little demand.
Ran across an interesting statistic the other day. At the time of the Revolution, Americans consumed about 2.5x the alcohol we do today. Today that would make us the heaviest consumer of booze in the world by a considerable distance. Higher than Belarus or Russia.
Possibly some of the recreational use of drugs was displaced back then by higher use of alcohol.