Ok so the point is if you didn't do the punt you dunno if it's true? Hmmm maybe, but would you know any of mine (or vice versa) are true. Certainly if someone expected me to do it they would need to have gained a bit of a history on here because I would be taking responsibility for the review.
Problem is as I see it, if you did a review of a punt you had, it could be challenged by others good or bad. If you or I posted one for someone else it can't be directly and thus it becomes as useful as an AW or PN review. Marmalade is right it would be a breeding ground for fake reviews positive and negative and whoever posted them would set themselves up as a quasi mod, which is never a good thing.
The intentions might be good but it would end up being bad. Only Adam could really post a review on someone else's behalf as he integrity could not be questioned as he has the power to do it anyway.