Hubpages makes its income by advertising and the biggest source of revenue is AdSense. Hubpages could not operate without advertising income... neither could most web sites. That's what keeps it free for you to use.
You are given the opportunity to share in this income by becoming an AdSense partner then you will actually receive part of the income generated from those ads.
So, while you can't turn off AdSense you don't have to use Amazon or eBay or Kontera nor will they appear unless you enable them.
If you are getting good views then apply to be an AdSense partner. I was already an AdSense partner on YouTube before I started here so it was just a matter of plugging in my account number.
YouTube asked me to join AdSense and I have a number of featured videos from which I also earn income. Not a lot but something is better than nothing.