In other words, "at the time we paid/did not reverse this, we thought the payer account was good for it, but as it turns out it was funded via transactions that ended up being reversed, and now the account is in the red" is not a valid reason to claw back money.

And that makes intuitive sense as well: Only the paying bank has a complete picture of all account activities (including out-of-character/potentially suspicious ones), so it makes sense to primarily hold them accountable.