Indeed, an irreducible entity (albeit with describable, predictable, behavior) is not much better than a miracle. This is why Occam's Razor, insisting that our model of the world should not postulate needless entities, insists that everything should be reduced to one type of stuff if possible. But the "if possible" is key: we verify through inference and induction whether or not it's reasonable to think we'll be able to reduce everything, not through a priori logic.