To answer the question about Pitching Area vs On the Rubber; probably has more to do with keeping a more traditional type of Slow Pitch Softball game vs Not. The only issues between calling one vs the other, is “Pitcher walking on the rubber/area without pausing before delivering a pitch. It is much easier to get away with walking or stepping before you deliver a pitch when a Pitcher’s Area is used. Umpires can be deceived by the motions of a veteran pitcher. The other concern is the same as the batter’s box, when no lines are present then it is left up to judgment of the umpires to determine what 2’ x 6’ looks like. Again, a savvy pitcher can make all of his/her pitches look like they are coming legally from the pitcher’s area.