Copping and pollarding doesn’t require genetic identity. E.g. you can grow pears from the branches of an apple tree (they still have to be somewhat close genetically, which is true here).
Well... growing pears on an apple tree is doable but not really practical, pear and apple trees are generally not graft-compatible and they will need specific interstock. It's rarely done.
But coppicing, pollarding and daisugi have nothing to do with grafting. It's just that daisugi works with only one tree and its rooted cuttings, but no grafting is involved.
