The work itself obviously is not[0], but you need somebody to synchronise that stuff, especially to ensure reviews remain anonymous (to paper authors). This must be handled by a third party.
[0] not entirely true for edition, publishers generally employ a number of editors although these editors usually have a solid science background for obvious reasons.
Comments
This is not done by the publishers. They only provide an online system to do so. The editors and reviewers are other scientists.
The work itself obviously is not[0], but you need somebody to synchronise that stuff, especially to ensure reviews remain anonymous (to paper authors). This must be handled by a third party.
[0] not entirely true for edition, publishers generally employ a number of editors although these editors usually have a solid science background for obvious reasons.