True, but Amazon's conversion rate is likely the highest, probably by quite a bit since it's such a trusted store and has a huge number of registered users with stored credit card data.
and not only that, amazon pays affiliates a commission on everything that a user buys within 24 hours. so if a user clicks on an affiliate's link and purchases a recommended sound card, then the affiliate gets a commission. if the user also buys some diapers within 24 hours, the affiliate gets a commission on that as well. amazon likely drives more of these these "secondary' purchases than any other store due to the breadth of products they offer.