Sounds like there needs to be a “know your merchant” law. It makes sense to me that Amazon might not be liable, but it makes no sense at all that people can’t get in touch with the actual seller.
In this case, should the landlord/cloud provider/payment processor/shipper be liable for defective products that the seller sells? There's a plethora of companies that play one or more aforementioned role(s), and it so happens that Amazon assumes all of them.