No. But they should be allowed to grow whatever plants they want in their backyard because freedom. And they should be allowed to consume those plants (and derivatives) because freedom. The argument isn't totally about medicine. It's about what I'm allowed to do as free man in my own home. Provided nobody else gets hurt, what's the problem with that? Don't knock 'freedom'. Don't you believe that people should be able to own any guns they want and only get punished when those guns are misused (AND NOT BEFORE) 'because freedom'? It's the same argument. See the parallel, make the connection. It is essentially an 'assault chemicals ban'. Only the chemicals can only hurt the people who choose to take them. Special care needs to be taken regarding access by children obviously.
The chemicals don't only hurt the people who take them. Users of these drugs have altered states of consciousness and make irrational, dangerous decision that can endanger everyone around them. Difference between guns and drugs is that a gun doesn't alter the psychological state of the user making them dangerous to everyone around them.
Whether you have a FA rifle or a semi auto handgun, it doesn't make you more or less likely to commit a mass shooting. If you are high on PCP, meth, LSD, you are more likely to harm someone else than if you had a few drinks. Don't mistake what I said, I am not saying a drunk person cannot be dangerous or a drug user is always dangerous. I am simply stating there is an obvious difference in danger involved majority of the time.