I don't think that argument holds up to reality. In fact the saying "opioid for the masses" seems to indicate that drugs could potentially be an effective tool

I don't think that argument holds up to reality. In fact the saying "opioid for the masses" seems to indicate that drugs could potentially be an effective tool to control "the masses". There's a lot to criticise in the war on drugs. But I don't think it involves a conspiracy to stun some imagined society of free-thinkers. If I had to name the worst mechanism at play here, it's the tendency of people to buy into law-and-order rhetoric and the lack of empathy for anybody who is seen as (even potentially) transgress.