I feel the other way around. Basically there's no real reason to believe in leaving the body as you can easily, empirically disprove it yourself. In my view, if they follow the same process and one doesn't hold more possibilities than the other, they're most likely an experience in the mind alone. Certain drugs can induce the feeling of leaving the body, which I think points to it being psychological/neurochemical in nature.
RE: My Experience With Sleep Paralysis