Even without the lifestyle changes, you can get a 6+ month mitigation of symptoms, but without the lifestyle changes, the symptoms will return, and often it's an indicator of unhealthy lifestyle as opposed to a mental illness. Unfortunately, mental health and treatment with drugs ignores that all important bit. Maybe you are healthy, and are having a perfectly normal response to stressful, negative conditions, and don't need drugs. In the case of shrooms, it can suppress the obsessive loops and focus on being stuck for a long enough period that people can escape, but often that escape route has to be pointed out by a third party.

Unethical practices would be possible with psychedelics, still - don't provide the escape route, just keep people coming back for super expensive, slightly underdosed psychedelic trips every six months to mitigate symptoms.