I guess it’s suppose to keep the tree from rolling? Keeps the trunk on the stump? I am just a backyard hack, if it’s that precarious I leave it for the pros or Mother Nature.
I saw a tree service fell a large palm tree in my mother's yard using that technique. The guy said it was the best way to fell a palm tree. I don't know....
It's a felling technique for smaller diameter trees with back lean . It's so you can get a lot of lift and not sacrifice strength of the hinge.usually make that bottom bore cut and insert wedges before other cuts are made.