The studies are designed this way to keep the shaman in the equation when the drugs become treatments. Informal polling over decades shows MDMA is pretty impressive on its own.

We need a clinical study where a group of veterans with PTSD is given MDMA and an isolated quiet place to go for several hours. Each of them is told they're receiving a drug that cures PTSD. The placebo effect paired with the brain rewiring effect of MDMA will cure more people than any other method and demonstrate that the effect is self-contained.