Granite and cones is a little bit different story than a rigid rack. In the case of granite or say bluestone, it’s less expensive sibling, it’s really all about stiffness and harness, which are more desirable attributes than rigidity for isolation. You know, hardness for speed of dissipating energy from the system and the (stiff) granite slab to isolate against bending forces. There is also inertia benefit due to sheer mass of granite slab. Never take anything for granite. To improve upon the granite and cones place another slab of granite on top of springs on top of the first slab of granite, completing the Trifecta!