Taking advantage of that would most likely cause you to write an overly promotional hub that includes affiliate links. That is in violation of the HubPages' terms of service.
Also, knowing that HubPages is affiliated with Amazon in some way, I would add that they won't allow you to send referrals directly to Amazon. Those referrals have to pass through HubPages first, which is the reason we are provided with an Amazon content capsule.
If HubPages weren't benefiting from all that then all the rules for affiliate links would be something like "Amazon and Ebay links only. No more than 2 per page".
p.s. No hate to HubPages here - everyone needs as many possible income streams as possible.