I live in China and Amazon sellers here have access to this info, as long as they are willing to pay ... it's no problem to get the buyer info, or even get the review deleted.
Unfortunately, Amazon's policies make it almost impossible to try and help customers with issues without using the services of unscrupulous agents leaking the info out of the back door.
If somebody receives a faulty product and we want to contact them to make it right, we don't have the email address, the address to send a replacement or even the ability to contact them unless they contact us first.
How can you offer good customer service when your hands are tied like this?
Less than 1% of buyers leave reviews, and typically disappointed customers will leave negative reviews, which of course makes it very important to deal with customer service -- 1 or 2 negative feedbacks on a new product can kill its sales completely.
I remember my 3PL warehouse made a mistake on a new range of products and label the large one as the small and vice versa and of course customers started to receive the wrong products from Amazon and leave us negative reviews. Rather than contacting us for help, reviews stating things like bait and switch.
I wanted to contact all the customers who purchased the product and let then know in advance that they might receive the wrong size product, but this was impossible due to Amazon's horrible system, unable to contact them, unable to see the address etc ... and of course contacting them via other means like this article is out of the question for us being a western brand.
Almost 12 months of product development totally messed up by a warehouse error.