The positive side...'to hold a candle to'...meant to assist, in the sense in which an apprentice might hold a candle in a dark work-situation so that the master craftsman could carry out the work. To say that someone can't do that is to suggest that he is unfit even to do such a minor, subsidiary task. In other words, he cannot begin to compare with the other person being referred to. The positive version is certainly as old as the 16th century.