I wouldn't call priority output splitters a form of belt balancing, but I'll accepted there is some conceptual overlap. However:

If you're tapping off the side most lane it doesn't matter what balancer you have at the head of the bus, you have to "balance" it after that point.

Furthermore, if you need real balancers in the middle of your bus to prevent the later stages of the line from being starved, that's a failure to plan for sufficient capacity. Balancers are a convienent way to patch over that mistake, but that's the sort of thing I'm talking about when I say they're cope.