Feature not bug. Firstly, the high schoolers can't double play so they are out until the high school freeze ends. It would mean the youngers would go, there's a break, and then the high schoolers, which is hard to turn that machine on and then off.
Second, it's a way of getting year round soccer for the youngers since the way it's set up is pretty much a continuation of league play before tryouts and then summer. The way CalSouth was working is the tryout shuffle was beginning in Thanksgiving while whole teams reorganizing for state cup (stronger teams got stronger, weaker teams wound up having to sit out state cup since they were stuck).
Finally, I like the flexibility with rankings which again goes to why the clubs prefer the SoCal system. Teams with a higher PPG can apply to play up and teams with a lower PPG can apply to play down. It's not so great if you are trying to figure out who really is the true "champion" but after the top tier that distinction just becomes artificial line drawing