It contains most of the answers the user would like to know about. Yes, very much so. Basically companies are fighting for your e-business. Having referrals is just a bonus. Pyramids requires you get money from others.
Free money is very attractive by itself.
Just tell your friends about us and they will join by themselves. If your referrals refer more friends, they can make more than you. These new companies figured out that people are willing to put a banner on their screen for a cut of the profits. So that's what they do. You sign up, they put a banner on your screen while you are online, and they share the money they get from the advertisers.