The article states that "geography continues to have an impact on efforts to market through the Internet in ways that could help online merchants target new customers. Specifically, the papers examine the effect of economic geography on Internet retailers trying to reach potential buyers of specialty products who live in an area where their purchasing decisions make them a minority."
So just because anyone anywhere in the world can buy a product online, it doesn't mean they will. Understanding who your customers are, where they are located and the value that customer has back to a retail concept is applicable to any channel of retailing.
The article can be read in its entirety here: http://knowledge.wharton.upenn.edu/article.cfm?articleid=2455.