I'm not a fan of the US war on drugs (which is not really a thing in Europe), but there is a difference between weed and meth. One may ruin your life, one WILL ruin your life. You argue from a point of abstract principles, but miss that there is a reality.
Just as there is food safety and certain things are not allowed to be sold because it would be dangerous to you or harmful to the world to eat them, so some drugs also need to be illegal. If you don't believe that go and see any drug addict street, or visit a Brazilian slum where the kids waste away on glue fumes. At societal level high rates of hard drug consumption are unbearable and destroy any healthy community. Opium had two whole wars around it as it was forced into the market by Brits and French and destroyed the fabric of Chinese society with entire generations of men disappearing into (legal) opium dens and spending all their and their families' fortunes while wasting away and letting their children starve.
No one wants to be a drug addict and no reasonable person that has a basic understanding of what hard drugs can do can think drugs like that should be legal. Meth, crack and co are a dozen times worse than opium, not to mention krokodil or similar poison that will straight up destroy your organs from first use.
Portugal has taken the right route, with drugs still illegal but drug use not anymore criminalised, so they are getting people off the streets and off the drugs. There is no benefit in locking people up for using, as they 99% don't want to use - they just can't find the way out. But that hard drugs themselves need to be illegal and fought is without question.