Take someone that suffers from paranoid schizophrenia; telling them God speaks to people and that they should obey him can have dire consequences! I've see this problem first hand, so I'm not just speculating.
People throughout history have claimed to be profits; but unless they are a fraud, it's far more likely that the voices they hear auditory hallucinations associated with schizophrenia!
This is why I totally understand the point of view of the therapists having to deal with the long term effects on these unlucky people. Both sides have good arguments, one cannot ignore them, only trade-offs to accept one way or another.
A close relative had that since ~30 years of age until death at ~80 years of age. During his twenties he abstained. Then it was social drinking, then it became more frequent, then he started becoming dysfunctional, not being able to perform in his professional life, all the while his mental state degraded, around 50 years of age you could still argue with him, around 60-70 there wasn't anyone to argue with anymore, there was only a craving left.
I don't think it's just the alcohol. I presume that it concealed a psychological problem. But, I can't help thinking that if it were some other drug the person in question would have had a higher life quality. Alcohol is very punishing in all ways.
Even heroin can be used intravenously for decades as long as proper caution is observed, but that tends to become a low priority if availability and thus price fluctuates. If quality fluctuates, death by overdose is a matter of time. The opioid epidemic is no joke, but it took a turn for the worse once doctors stopped prescribing opioids and supplies dried out, making people pay inflated prices and/or switch to fentanyl.
At least alcohol is available, so people don’t drink mouthwash.
That's contrary to my understanding. I think you're overestimating the damage of one and underestimating the damage of the other. If you've underlying conditions susceptible to drinking or to smoking, indulgence in either can have dire consequences. For what it's worth, smoking for days straight is much much better in all ways than drinking for days straight.
Case point 1 but simple fact is, tons of people have some sort of predisposition to some form of mental illness. Wife is a doctor and she nicely sums it up - its not binary, tons of folks having miserable life are in scale 1-10 somewhere in lower part of one or the other mental illness (or more). Bipolar, OCD, ADHD, schizophrenia, etc., you name it. She deals with them daily.
For some, weed could trigger it. For some, some other drug or some big shock (close relative death, accident, violent crime etc). Since we don't ban the rest, banning the weed is just cargo culting due to US policies re hippies from Nixon era, enforced globally due to UN treaties. Which led to ridiculous situations where places like India or Nepal having marihuana as holy flower of god Shiva for literally thousands of years, using it to celebrate him, and suddenly had to ban it... at least on paper. Because bureaucracy.
Your father is not a good reference for this topic, its often a sad story when such people are asked to make policies that govern us all. They are always 'too deep' in the problem, see only the worst cases, so inevitably for them its the source of all evil and extremely dangerous. They don't know how happy, connected with nature and universe one can feel, how sex can be 10x better than best one he ever had, and orgasm can be literal nuke in your cranium, by far the strongest experience in ones life. Or tons of other, positive effects if not used in excess.
Ask doctors who work on alcohol rehab clinics whether it should be banned. Most will say definitely, and those who don't simply because they use it to self-medicate depression. And that is only because its socially acceptable drug, although way more destructive than weed could ever be.