You have an incorrect fact. Not all dispensaries in all states have to be vertically integrated.
In fact, in Illinois the law states that the MSO's have to supply non-integrated retailers.
In NY the MSO were grandfathered in. Otherwise new licenses are going to be divided between cultivators, processors/manufacturers, and retailers.
It's very confusing but they are obviously trying to prohibit monopolies and behemoths from taking over. They want "the-little-guy" to have industry ownership access.