Its not about being left to professionals. This advice is to prevent suicide attempts by individuals who are feeling extremely negative with no hope. Psychedelics amplify your current state of mind. This means negative thought patterns are amplified, so an individual who may not have been suicidal previously may become so especially if they are alone.

Personally I think psychedelics should be freely available to any human that wants them, however I'm also aware of the dangers that these compounds can present and as a society we need to be aware and prepared to face these things. That includes the awareness that one should be careful about their mindset when they decide to use such a powerful tool.

I also agree that there are incompetent professionals, but this isn't about competency. Its about preventing suicide.