Pretty much the same thing that was done with opiates. A natural plant that has received alot of demonizing by the government but still one of the best pain managing narcotics out there and it can be grown in your back yard. But because they can't make money on it if its growing in your vegetable garden they lobby to get it banned.
I know I'm mentioning one of the unmentionables but I'm just using it as another example of what happens when big money gets invovled. There is not a plant on this planet that should be outlawed. All these plants are here for a reason.