Mark, I think the idea is that the plant is spending energy when it first pushes out the new buds and leaves. After that, maybe the new growth can sustain itself by photosynthesis.
The main plant is still diverting water and other resources from the ground to any side growth. If the growth becomes really vigorous, the plant could decide that it is now the main plant and give it the majority of the ground resources. If there's enough water and fertilizer around, maybe that's totally fine. Just my reasoning based on my feelings.