^I think the OP is referring to the period of legal psychedelic use during the late 50'/60's as an informal 'social experiment'.
People may put too much faith in the ability of psychedelics to spontaneously enact change within an individual. This effect is hard to define because it may be non-existent. From there, it follows that widespread change initiated by psychedelics occurring across society in general is even more unlikely. All the stuff that was happening in the sixties only featured drug use as a small component; the rest was a result of World War II (baby boom leading to an increase in young middle class people) accompanied by sexual liberation, reliable birth control, civil rights and a global culture related to technological progression (cheap airflight, radio, television, electronic audio reproduction, etc.). In truth, the idea of a psychedelic society has not failed because it has barely been attempted.