On Joint Carving

Sider seems to imply that there are theories that better outline the nature of reality by carving it at it's "joints". Yet isn't the purpose of metaphysics not to try to get "close" to outlining the nature of reality but rather create a full and vivid picture? Of course that's a metametaphyical question but one I need to ask. And now back to Ontological Realism. Yay.