Community vs. Social Network

Michael, okay, we can believe that we can reach everybody on our Earth through the chain (maybe throuh the very long chain) of our acquaintances. I will give you one example which can cast doubt on this a little lately. But my main question is about what does it mean for us that we can reach everybody? What consequences do we have? How can we use it? And what does it give to us - as for humans, brands or service developers - in opposite to community restrictions? 

p.s. One little example that casts doubt on ubiquity of the globe social network.

One author from habr.ru tried to examine the theory of six degrees of separation. He got the data of "friendship" between users of Vk.com (also known as Vkontakte), the biggest socila network site in Europe (this is a Russian counterpart of Facebook). And then he found that about 50% of all users are grouped in isolated cliques that don't have any relations with other part of the network or just have just 1 connection. He had to exclude thу data of these users from his analysis arguing that all of them are fake accounts. But it's rather strange because Vkontakte has more then 100 million users. Here is the link to the article I told: http://habrahabr.ru/blogs/data_mining/132558/