I've seen some posts on other forums that suggest that planting the graft below ground may allow the tree to sprout from the scion wood and get on it's own roots, instead of being on a root stock. Now if you are on a dwarfing root stock, I can see wanting to avoid it. But in some cases I've heard of graft incompatibility that can take years to present, or you have a root stock that tends to be short lived (E.g. grafting plum on nanking cherry). Would overplanting the tree above the graft allow it to develop onto it's own roots?