However, it does produce blurred images - that's why it isn't always on. In the case of animation, where motion blur is desirable, the directional nature of this blurring is positive, but static elements will be blurred. Almost all post-processing is image blurring: bloom, film-grain, depth-of-field, lens flares, motion blur, HDRI, etc., etc., etc. People like blur, that's the reason there's so much interest in separating out the render elements (diffuse, specular, mirrors, etc.) - so they can be degraded to varying degrees before recompositing. That's the art.
Martin Hash