The biggest problem with people trying to figure out if cannabis is medicinal happens to be the huge variety of quality/contamination with cannabis. Folks in prohibition states are usually only exposed to contaminated and poor quality cannabis.

The other issue happens to be the huge amount of recreational strains of cannabis, drastically low in CBD content. Prohibition (and the inability to easily/cheaply test for thc/cbd) has caused most breeders to focus on potency of the high/stone. When this is focused on, without testing for actual thc/cbd amounts, you end up with high THC, very low CBD strains.