This is certainly unethical. Sadly, it is really difficult for Amazon to track. Amazon didn't say you can't purchase the item and resell them at a higher price.
This is like saying using the points from your credit card purchase toward gift cards or certificates. Then flip the gift cards for cash. No one really get hurt from the transactions. Amazon got their cut. Seller got their cut. Buyer got what they want.
This is like saying using the points from your credit card purchase toward gift cards or certificates. Then flip the gift cards for cash. No one really get hurt from the transactions. Amazon got their cut. Seller got their cut. Buyer got what they want.