Cagey as fuck, consequences of legalities, first ones over the top getting struck off, lack of integration in training with psychology postgrads, fear of being sued from patients. It’ll take more than Carhart-Harris preaching to the converted.
Privately, don’t think it would take too much looking to find a guide. The networks are already established. Very much live, but trust is understandably an issue. It’s small matters like serotonin syndrome that get missed in questioning. Eg NHS repeatedly failing to mention that condition when prescribing anti-depressants combined with clients known to engage in recreational drug use.