Absolutely. You need some way to prove that the reviewer is acting in good faith. With Amazon reviews, I ignore most of the 5-star reviews and focus on the 2-3 star reviews (1 star reviews are often worthless), mostly because 4-5 star reviews seem to frequently be biased (free item, out outright purchased/fabricated review).

How about compensating reviewers relative to the "helpfulness" of their reviews? Maybe allow manufacturers to refund X product purchases for reviews, but with zero control over who does the review and zero knowledge of which order is being reviewed (can't send golden samples). That's basically how "mystery shopping" works, but that seems to not be a thing with online retail.

There are a lot of good approaches here, but this seems like the only benefit is that it separates the reviewer platform from the retail platform. It's still ripe for abuse unless reviewers have more incentive to be honest than to be bribed.