I do agree that drugs were often needed for people to ensure the hardships of civilization (alcohol is not just a disinfectant). My main problem though is that this is too often used as an argument to shove a bunch of drugs in the general population, when we maybe could achieve some better results by just improving society.
The people that take psylocibin/mescalin/whatever always tell other how much it expanded their mind, yet often they seem just as narrow minded to me as they did before, just in a different way