I saw one where the tree was between two buildings, tight. No room for a tether. Tethering to the stump would probably have been too slack. Faller was more of a faller than an arborist. He made his key long and it seated well. Pine wiggled on landing but the butt didn’t go anywhere. Maybe I’ll try to find it.
Only other thing I could see is wide open gap face in hingy green wood that held to the ground. Or lag bolt metal hinges to the sides of the tree…
…or piece/crane it down so it’s a non issue.
That’s the only real use I’ve seen for it and it’s a narrow range of use. Well, maybe for dead wood that doesn’t hinge too.