Facebook seems to be making it more and more difficult for a user to see just "a feed" with all their friends' activity; instead they optimize things like this and show users only what they think they want to see, and hide everything else.
Not sure why this particular activity is noteworthy. The 'dirty world' described here is much, much larger. 'Affiliate Marketing' is a very broad activity that involves doing the least possible work to generate a lead or sale for an affiliate for which you will get paid, and this is just an example of that.
We're assuming here that EdgeRank takes outliers into account in a positive way. It's entirely plausible that they work with medians for example.