You’d be shocked how quickly the feeder roots come back, if the tree is adequately hydrated before planting and watered after planting. Also, a fully dormant bare-root tree will not put out any more top growth than its roots can support. Top growth is encouraged by hormones coming from the root tips and discouraged by hormones coming from the shoots. Roots are likewise encouraged/discouraged by the inverse set of hormones. Any time the hormones get out of balance, the part that is less inhibited grows more until the hormones are in balance.
I’ve had trees that come as you describe, that I did not do any top pruning, and they put on lots of healthy growth the first season. I seldom see the “sleep, creep, leap” pattern on bare-root trees and shrubs, with the possible exception of persimmons. At worst, I get “creep, leap.”
The ACTUAL reason they ask you to do that is that it’s the easiest way to explain how to train a fruit tree to the masses. Not necessarily the best and certainly not the only way to train a tree, but it’s easy to understand. Also, the “feathers” on a young whip are often too thick in proportion to the trunk. See @alan 's “Pruning by Numbers” post for more on that.