The cone does not "usually" get pitted if properly maintained. I have had hub and other bearings in the past last for many years and thousands of miles without pitting. In fact, I highly value a hub that has some wear, as the cones and cup wear surfaces are much smoother than when new. As noted, if only the cone is pitted it's better to replace it than to try such a hack, as the bearing will not operate as well and could be difficult to adjust.