Pretend we have a pool that is vastly over target all the time, driving the cost of liquidity provision down compared to all other pools. Shareholders are satisfied with the level of liquidity but find that the buy:sell ratio of the pool is often out of line with the rest of the network (assume the pool is the biggest pool, but is still significantly smaller than the sum of all other pools). The shareholders start talking about the ideal split of the pool with reference to the network. Let’s be those shareholders.
If there is more buy liquidity in the network, but the local pool is balanced, other pools will apply pressure to the pool to go out of balance. We can reduce this pressure by paying the network heavy side more than the network light side. The concept here is that if the network itself is out of balance all custodians have a common pressure to switch to the lighter side, tossing the network out of equilibrium. By adjusting the local asymmetry to reflect the network asymmetry, we can relieve this pressure.
Another thing to think about is that we may want more buy liquidity in general than sell. How much more? This is a network concern, do we want for example 2x more buy liquidity than sell across all 3 tiers?