Let's follow this logic though (and it is logical) everything has the potential to be used harmfully, even oxygen and water. Everything has the potential to be used harmlessly heroin, pcp, and crack are all safe if used carefully.
I think "do no harm" is a great rule but it requires determination and judgment and that's what this voting is for. It will always be a judgment and unlike IRL it isnt enforced by violence or kidnapping, it's just a matter of inclusion and exclusion. even then it's not so harsh, little biggy is a monopoly on nothing and impedes no one.
There are a LOT of folks with cancer here, people that discovered cannabis as a treatment for the tobacco that is killing them. To me that's why it just doesn't fit in here.