Sculpting and rigging are not friends at all, the mesh density and bad topology that comes out of sculpting is not compatible with rigging. Those brushes you see for posing in sculpt mode is not rigging per se, it’s just a tool that imitates rigging so you can pose your sculpt with much easy if you so desire. Before those tools, trying to move parts of your sculpture was next to impossible. Those tools now provide a way to fiddle with your sculpt enough just so if you wanted to tweak a pose.
