Actually, I think the current rating of a relay has more to do with the transitions between on and off than the current that can be carried in the "on" state; sometimes you can "cheat" if there won't be current trying to flow during the actual on/off events. (but the conclusion is the same as retro/etc.)
Simple mechanical switches have similar ratings and similar issues. As some people discover the first time they try to discharge a HV cap through such a switch...