Medical marijuana isn’t a cure, its a treatment. The point isn’t to make medical problems go away, it is reduce the adverse impact (more effectively and/or with less of its own adverse side effects than other alternatives.)

We do use it, and it does work, and “we” were using it for those problems even when it was illegal, a condition that didn't not occur as the outcome of a rational evaluation of scientific evidence of utility vs. harm on either recreational or medical use, but based on vibes (and, in no small part, racism.)