In this case this is about spiking the CD in the top seller charts / search results. Amazon is limiting purchases due to the increased returns from random buyer

In this case this is about spiking the CD in the top seller charts / search results. Amazon is limiting purchases due to the increased returns from random buyers who buy it and immediately return. They could probably limit the number of returns to 4 instead of purchases, but it might be complicated legally due to their return policy (i.e. they'd need to update the return policy and inform the customer.)