To be honest, I'm not sure who came up with this system. But you are right, in order to maintain a high average, you need to go for the runout at virtually every opportunity. Then of course, any missed runout with only a couple balls of yours left, gives your opponent an easy chance to get out himself.
You basically need to break and runout at least once, at least every other league night, in order to have one of the top averages. I actually did runout 2 times in one night this year, and the third game that night my opponent broke and ran out against me, to prevent me from an opportunity to get a perfect night.
EDIT: After thinking about it some more, I think that because this is a bar league with a total of 15 games to play a night, to speed the games along, this type of total offense scoring is probably an attempt to make all of the games go faster.