The FBI certainly seemed to think so, concluding that John Lennon wasn't a "true revolutionist" because he was "constantly under the influence of narcotics". The Bureau might have a point. Exactly how many successful, stoned revolutionaries, sorry, revolutionists, have there been?
My research cannot match that of the FBI, but even so, things do not look good for the expanded minds. The lasting achievements of such advocates of change as Jerry Rubin, Abbie Hoffman and other Haight Ashbury habitués speak for themselves; "peace," "love", "heavy", and "don't bogart that joint, my friend," never had quite the same blood-firing appeal as, say, "give me liberty or give me death".
Of history's top overturners, Cromwell died rather than take a drug, Marat wouldn't have been available for stabbing in his bath if there'd been one for his skin condition, Marx preferred a pint, Lenin was a coffee man, and Mao only succumbed when he was aged and ailing. Even the great Che, whose poster has witnessed any amount of assisted activity, was more into rugby.
Actually, the FBI could have saved themselves a lot of covert surveillance by listening to Lennon's great anthem "Revolution", which concludes with lyrics to storm barricades by: "Don't you know it's gonna be alright, alright, alright." Indeed. To the sofas!