Companies should not be liable for user input. A company, such as Yelp, is merely providing a forum for people to express their opinions. It would be the equivalent of holding a stadium responsible for a speaker's defamatory comments. Establishments are suing these companies in order to suppress negative reviews, which is in violation of free speech.
Yelp is only a way for people to broadcast someone's opinion. They are not responsible for it. I think that the company with bad reviews should focus on fixing the problem that is being pointed out instead of just trying to blame someone or something for what is being said.
They also should not own the content that users post to their site. Websites merely give people a platform for expressing thier opinion and they should not be liable for what people say. If they were this would result in censorship and these kinds of websites would no longer be reliable.
It is my opinion that companies that are based on user input and user opinions should not be held liable for what the input is. This is especially true for a site like yelp, where users are reviewing restaurants and businesses so that other customers can make informed decisions. Therefore, I think that the individual business listed on yelp is responsible because the user input they receive is directly linked to their customers' experiences. If they want to have high star ratings and good reviews, then the individual business needs to provide the utmost quality customer service and experience.