Beware of this point, it could backfire. We can only imagine what length a competitor would do to defame their fellow competition. For example, without having to submit a proof for bad review, a company called worstexchange could create hundreds of accounts to wrote bad review about his fellow competition, goodexchange.
Yes, but for the other hand, now we have the opposite situation in which all the positive reviews aren't moderated by admins of ratings. So exchangers write positive reviews for themselves. And I don't see many bad consequences of this. The problem is bad reviews become gray, not good reviews posted without proofs. Also there are sites like WoT and Trustpilot. They don't check if you actually were a customer when you post a bad review of some business. Of course competitors write bad reviews to each other but it doesn't harm WoT and Trustpilot and doesn't turn these websites to battlefields. So, theoretically I agree with you, but practically I don't see the situation described by you on reviews websites.
And without an admin who can moderate or decide the legitimacy of those fake reviews, your system would turn into a battlefield of reviews before ultimately collapsed.
And as for admin's power. Wikipedia is created by community and it's ok. And I'm not saying moderation isn't necessary. For example, if some users say worstexchange asks for kyc I think I should read worstexchange's rules and maybe speak with worstexchange's admin to check if these users tell true. But moderation (in the meaning of checking if some info is true) and power aren't the same thing. I mean, there won't be an admin deciding "I'll make this review gray or delete it because I want to" or "I won't put this icon because I don't want to".
Also I think nothing is perfect. If I create the exchanger rating and see it doesn't work the way I expected so I'll change things that don't work as expected.