The ratings thing is a blip for them. Only sophisticated customers are aware of it... and sophisticated customers are the exception, not the rule.
It doesn't take an extraordinary amount of "sophistication" to notice that the products that you ordered are cheap, broken and/or counterfeit trash when they arrive. They don't deliver any more quickly than anyone else anymore either. Unless you're on Prime; I think they prioritize Prime.
My experience with the products I've received ordering from Amazon has generally been very good, comparable to products I bought in person. Things are generally as advertised, and work correctly. My guess is that Amazon is doing well because mostly people have an experience similar to mine, and are happy to keep ordering?
I thought they made a smart move with their own branded stuff but a lot of this is just as bad quality.
There is much more wrong with Amazon, but they survive and thrive simply because of their scale.
I had one order last year where I was unhappy with Amazon’s treatment on the issue. They were willing to give my money back without hassle, but that wouldn’t fix my wife’s car’s charging system, so I had to make something work.