Visionary art is a lot of ways true surrealism, or what surrealism was supposed to be, I feel. On a basic conceptual level, it is fantastical realism; which is to say, the point of it is to use abstract or dreamlike or surreal or spiritual themes to express very human and emotional truths and experiences. To make a complicated world or event that represents some larger feeling, or desire, way of thinking, etc. My one problem is some people lean too hard on the use/veneration of drugs.
drugs != spirituality