How deep to plant grafted rootstock/appletree?

[lordkiwi]

there is already a thread that might cover your question

Good or bad to plant trees with graft below soil?

Some people seem to do this to encourage a tree to grow on it’s own roots. Other people say this can cause rot and hurt/kill a tree. But those two ideas seem to be at odds with each other. Is it that only some types of trees are likely to grow their own roots?