I never soak roots of even whips from a commercial nursery, I make some effort to keep roots moist while out of the ground and make sure the soil is at or near maximum moistness when planting, but I don’t fill holes with water as the literature often suggests. I don’t believe some air pockets are bad as long as soil is moist.
When transplanting plants in leaf it’s a different story, I tend to water my vegetable starts in.
The fine roots are mostly lost when transplanting while larger roots are sealed with suberin and are not in danger of quickly drying out. The advantage of bare root transplanting is that it’s easier to move a lot more large roots which have their own protection from dehydration but moving rootballs allows the preservation of more fine roots.
If you move a large enough ball you can move trees in the middle of summer without any shock at all, but it’s extremely labor intensive and large balls can weigh tons.
For some reason, trees without a fibrous root system like pears and persimmons are difficult to transplant bare root. Even whips sometimes take a long time to recover from bare root transplanting. Once pear trees get larger than about 2" diameter, BR transplanting becomes dicey- I have lost trees. In my nursery all my pears are propagated in in-ground bags and never moved bare root after the initial planting.