You have to balance the risk with the benefit. If overall it helps, don’t restrict access to save people from some pie in the sky threat.
The dangers of marijuana are quite real. Marijuana contains carcinogens more potent than those found in tobacco. Marijuana has been shown to precipitate psychotic disorders in immature brains. Marijuana decreases initiative. Marijuana use has been connected to certain mental abnormalities in offspring, even offspring who were born years after the last use of marijuana. These are not "pie in the sky threats"--they are real dangers of marijuana use. I am not convinced that the seizure repressing activity of marijuana--if it exists, which has not been scientifically established--is better than that of current approved seizure medications. I sense here a situation where rumors claim all kinds of miraculous properties of some drug, but no tests have ever been done and there is no clear evidence of miracles. This usually happens in the realm of cancer "cures."