I guess you could argue that Amazon is in a unique position somewhere between, say, Craigslist (which simply allows independent sellers to connect with buyers and should bear little responsibility for counterfeits) and an old-fashioned mom-and-pop (which buys goods directly, choosing legitimate or illegitimate wholesalers and handling the merchandise). But everyone is in-between these days.

And the time for a defense from ignorance is long past...

Are you sure? The linked article said that the retailers that were busted were part of the scheme, doesn't sound like they were innocent bystanders that were cheated by the distributors.

Three retail businesses in Queens and two in Manhattan were part of the scheme, Mr. Melendez said, adding that they had closed

I've sold new items on Amazon (fulfilled by Amazon). I assure you, I provided no such paperwork other than me marking it as new when I set up the shipment on their site.