Comments:

"Affiliate programs were built on a false pretense: affiliates always deliver new customers and are always, solely, responsible for creating the sale.” Okay. This here statement is incorrect. No one ever said that was what affiliate marketing was ever built on.
Furthermore, affiliates do bring in new customers or at least eBay believes this. They pay for new registered users. You’d think everybody was a registered user of eBay already? Incorrect. There is always more market out there.
Finally, the 30 day return period is a myth. The vast majority of orders appear within 24 hours of a click through.
But back to the original point - it is reasonable for merchants to crack down on affiliates that do not provide value as with the two examples provided above. Of course, merchants have been doing this for years already, or they should have been.