Psychedelics provide a incredible jolt to the system (at least that's what they tell me) but if they do provide health benefits I believe they are short term, similar to traveling to another country or doing something unusual with your life. On the other hand, people that take psychedelics too often tend to have long term negative consequences such as anxiety or become dysfunctional in other ways. It's very hard to have nuanced opinions these days, but I think society in general needs to come to terms with psychedelics, the dangers they present, the novel experiences they enable, and some mental health benefits they may enable.
I am under the impression the United States pushed hard for the international treaty in 1961 that required these drugs be prohibited in most of those countries.