Not true, I could set up a WordPress blog and start writing reviews. As long as it stays a niche thing I share with a couple of friends online, that “review platform” won’t be gamed or flooded by fake reviews.
My point being that closed “publishing” instances can be reliable.
While I cannot think of a better decentralization example, the lack of source code makes me worry this solution would not satisfy the open source software (OSS) criteria.