Reddit works in many (not all) cases for reviews because if there's something falsey enough, you can often count on the hive mind to provide many points as to why that is fake, links to reliable sources on better info, or alternative experiences and documentation (photos/vids) to back it up. Unlike retailer sites or Amazon, where the platform has a vested interest in just getting you to hit Buy, Reddit has no such issues, and there's no real policing of dissenting reviews.
It is self-policing in some ways. But again, some review categories are better for this than others, and the hive mind can be susceptible to hype and astroturf.