silk road was on the dark web, a place that is oriented 100% around anonymity. This precludes any sort of "elimination of fraudulent reviews" since there's no reasonable way to build any sort of chain of trust.
I explained several ideas to eliminate fraudulent reviews in my comment, that you didn't address. The main thing is to make a review coupled with a purchase that involves a large cut to the platform, so each review is very expensive. Secondly, don't take reviewers themselves seriously unless they've also made a large overall number of purchases to a diversity of sellers- making becoming a credible reviewer also expensive.
The dark web is based around network anonymity.
You can find, and log into, your facebook account, should you have one, here, where I'm sure you would be quite identifiable.
facebookwkhpilnemxj7asaniu7vnjjbiltxjqhye3mhbshg7kx5tfyd dot onion
anonymity doesn't preclude chain-of-trust (really "reputation").
after all, anonymity only means "can't be linked to real-life identity".