So if you start a great successfull referal business , you can make a lot of money by virtually doing nothing.
I wouldn't say you had to do nothing...
Making a good referal website takes a lot of effort. Your site design has to be appealing, the backend of the review script has to be solid, the server has to be OK. Also, you'll need to put a lot of time and effort in your reviews, the SEO part, tracking your payments and finding new sites to review.
I think the job of an affiliate marketer can be more tedious than the job of the webmaster you're referring visitors to.