Originally Posted by punkworld

It's by far the best way to reward those who send traffic in the best way without harming other affiliates. If someone is sent to a site, doesn't join immediately but comes back and signs up by himself a few days later, the affiliate probably is responsible for that. If someone sends a semi-blind hit, the surfer clicks the site away, but is later sent by another affiliate who actively tries to make the sale, clearly the semi-blind hit shouldn't get credit for it.