Sending out friend requests on LinkedIn or FaceBook is fairly easy for Americans but I bet it is less so for other, less gregarious cultures.
For example, I would guess that in Japan there would be fewer "friends" requests coming out of the blue. Same in Europe, especially in the UK, where I'm from.
Here in the US there is a culture of acquaintances which is not as developed as in other countries, or at least the countries I am familiar with. The culture of acquaintances is that I know a lot of people, and I like them, but I don't know them quite as well as my friends.
But that distinction doesn't matter much in the world of the social networks, and in the world of blogging, and Flickr, and Twitter--the whole trend to share oneself with the world...
But what if you are shy, what if you don't want to be AlwaysOn, always in conversation, what if you want to listen to your internal conversation, what if you value your privacy, your personal moments that you share carefully and uniquely? Will those people be at a disadvantage in this new world?