Affiliate Marketing on Social Networks

Is it worth it to build friend lists, followers or fans (whatever it is called) on social networks, talk authoritatively on a subject and occasionally sneak in an affiliate product fervently hoping the person would buy it?

Forrester research indicates that it is not worth the effort. Here is their argument:

62% of US online buyers are on social networks like Facebook to solely to communicate with their friends. Only 2% of those have ever purchased anything online. In that case, using social media marketing for affiliate product might not be a correct strategy.