Psychedelics open your brain up to rewiring in some way, and can be used under direction to treat a lot of things. But of course, people who didn't like the Vietnam War used them recreationally, which is why the US government made them globally illegal.
Charitably, you could argue a functional society involves some amount of indoctrination into a set of shared beliefs and a large percentage of people losing that indoctrination would destroy society. Could the US function if everyone was a pacifist, anti-capitalist, hippie? I think that was and still is the primary concern.