Yes, everyone knows where motion blur comes from in a real camera, but in a rendering view, there is no real camera. The renderer is what applies simulated motion blur. There are some simulated optical effects must be accounted for in order to render a realistic motion blur, like depth of field. Motion blur is quite often added to stylized animation in an equally stylized sort of arcing cloud, which requires the renderer to also have knowledge of the literal 3d model that's being animated.