The peers of the creator of an artefact also review the artefact.
When reviewing an artefact that is produced as part of the development process, the other people who could have produced the artefact are represented as reviewers of the artefact.
Peer review gives two-way transfer of skills and knowledge. Any skills transferred to the creator of the artefact being reviewed can be put to immediate use in improving the artefact under review. It can also act as a sanity-check; where the creator has forgotten something, another pair of eyes could notice the omission.
Note that when DevelopingInPairs, if the pair are peers, then there will in effect be reviewing and feedback as they go. One should not arrange work so that is always the case, because other forms of pairing can be very beneficial.