I was the operating manager for a small fashion company in Los Angeles for 2 years.Roughly 95% of our sales were on amazon. We primarily sold leggings, but did well in other basics too. At some point, fake negative reviews started flooding our store, but we didn't receive an increase in contact from customers complaining about the product. It was clear that a massive competitor was buying our product, leaving a bad review, and then reselling our products on their store. I confirmed this when I found another amazon store using our photos and descriptions.
Amazon didn't do shit about it. Our complaint was ignored. Our ratings tanked, and business slowed. We countered by buying fake reviews from a Chinese firm, and that helped us get back up to the coveted 4 star rating.
Amazon is a race to the bottom. I've left that company, which I liked, and I'll never use Amazon again. It kills businesses.