The box is brilliant but I don't understand the recommendation to bury the young tree in up to 4 inches of sand after removing the box. It doesn't seem natural

The box is brilliant but I don't understand the recommendation to bury the young tree in up to 4 inches of sand after removing the box. It doesn't seem natural and wouldn't it stress and possibly suffocate the small roots and trunk base? It sounds worse than a "mulch volcano". The hemp cloth could be staked to the ground and a small amount of mulch or nearby soil used instead.