It is not good for consumers. You buy from a particular seller because you know based on reviews that their item is not counterfeit and then amazon sends you the item from someone else and it is.
The major logistical advantages outweigh the very low possibility of abuse. If you asked the average consumer if they would like to receive their item 2 days faster, but risk a 1 in 1000 chance that they get a bogus item they will need to exchange with Amazon at no cost, I think the former would win by a mile.
The chances of getting a counterfeit item in some product categories is basically 100%. Go ahead, try to buy a real pair of Apple iPhone corded headphones on Amazon. That assignment is quite literally impossible.
Here, buy from Amazon direct and you'll get a real one.