The distinctive feature of recapitulation is that it works by correspondence rather than by exchange. Nothing changes hands. Instead the second figure walks the same ground as the first and, at each point where the first failed, does not.
Irenaeus builds the correspondences deliberately. Disobedience came by a tree and obedience comes by a tree. Death entered through a virgin's consent to a message and life enters through a virgin's consent to a different one, which is why the Eve and Mary pairing belongs to this account and not merely to later devotion. A man was defeated by hunger in a garden and a man refuses to turn stones into bread in a wilderness. Even the ages of life are covered, because Irenaeus holds that Christ sanctifies infancy by being an infant and old age by drawing the whole of human living into himself.
The reason for this insistence is polemical, and knowing the opponent explains the shape of the argument. Irenaeus was writing against teachers who held that the material world was the botched work of a lesser power and that salvation meant escaping a body. If that were true, then a saviour who took a real body and a real death would be doing something pointless. So Irenaeus makes the body the site of the whole operation. What is saved is what was made, by the same God, and the crucified flesh is the hinge.
It follows that recapitulation cannot be lifted out of its setting without losing its force. It is not offered as an answer to the question of how a just God can forgive, which is the question Anselm asked and which the later Western models are built to answer. It is offered as an answer to whether the creation is worth saving and whether it is the same God who saves it. Read as a reply to Anselm it looks incomplete. Read as a reply to what it was actually written against, it is doing exactly what it set out to do.