Jay, I've heard that its better to let the tree decide if, and where it need to lose some foliage, rather than guess at dosage and location. I know a lot of people want to prune before, but don't know if its really proper for trees.
I might wonder if gardeners are just doing 'work' because you are 'supposed to', and charging for their service. A local landscaper taught my old groundie that the way to loosen up a circling root ball with with an axe, chop those circling roots. Personally, I go for teasing out or a handsaw as needed. It could be that young trees can handle that big dose of pruning wounds, and just persevere. Enough roots and water and good soil might keep the crown alive and photosynthesizing enough to grow new roots without dieback. I don't know for sure. Seems like another sensible line of reasoning, that may or may not reflect reality.