https://www.techdirt.com/articles/20210113/15153146047/content-moderation-case-study-yelp-attempts-to-tackle-racism-platform-2020.shtml

Summary: Running a site that relies on third-party content means having to deal with the underside of human existence. While most people engage in good faith, a small minority of people engage with the sole purpose of disparaging others.

Yelp is no exception. Designed to provide potential customers with useful information about goods and services, the site's popularity lent itself to brigading (negative reviews delivered en masse in response to current outrages) and the lowest common denominators of the general public: bigots.