You obviously have no idea why cannabis was banned in the US.
It wasn't banned because of harm to individuals or to society. It certainly can do those things, but there was no scientific basis for the original ban.
It was banned because of a massive propaganda campaign by Harry Anslinger, who fabricated evidence that cannabis was a drug of immigrants, non-White Americans, and criminals. Anslinger was incredibly racist and had no respect for science or the truth.
He once said, "Reefer makes darkies think they're as good as white men." If you think we're "rediscovering why [marijuana was] banned in the first place," you could not be more wrong.