That ruling was put in play because the 2 liner, female only, SoG/NJ and Burial sometimes made it impossible, or extremely difficult to get to 5. The fact that SoG can not rescue any lost soul was a heated debate because of the NT only and female only so the new SoG came out to fix that issue. Then rescuing your own went away to improve gameplay. Burial, SoG/NJ out of 7 lost souls leaves your opponent only 4 to rescue before soul generation was really a thing, only harvest time was available/used. So this ruling enhanced gameplay, IMO, and was the reasoning behind the change.