That's what I meant with shady business practices. Well, also the fact that they receive payments to remove bad reviews.
Haven't heard that about Tripadvisor...
This is a superficial view of Yelp. They do not create reviews. They have a business plan where businesses can filter out some reviews, but this does not allow them to filter out all bad reviews. Yelp works pretty well in the U.S. I use it very often, I posted many reviews, and I have always been very happy with the results of my searches and the community itself.
And Yelp is very different from Tripadvisor. The latter is for tourists, the first is for locals. If I check Tripadvisor in my city, I'll find places that are so touristy that I would never visit. Yelp gives me all the most updated restaurants and shops.