Primacy Of Consciousness
Most mystical metaphysical notions start out as an explanation for some phenomenon -- the sort of explanation found in many old Greek myths that we laugh about because they seem so far fetched today. But there is a sort of internal consistency within each one which explains why some of these have persisted. They do successfully provide an explanation for something, it's just that that explanation might not be true.
The common fault with many of these metaphysical notions is that they are arbitrary, meaning without any basis in reality. Sure, Persephone getting abducted by Hades and then later rescued by her mother Demeter will explain why the seasons take place, but there is no reason to choose this explanation instead of "the legend of the flatulent goat who drastically alters the weather throughout the year".
When a theory or belief has no grounding in reality, it is not useful and is usually harmful to some degree. If you believe that making sacrifices to Demeter will hasten Spring, that belief is harmful to you by cost of whatever you sacrifice, because springtime will not be affected by your efforts. To believe something without evidence, or even worse against evidence, can sometimes be quite harmful.