Today, communities are becoming more and more disorganized and focus more upon the individual than upon groups. There are several theories behind this disorganized network community. One of them is that of the nation-state in which a large scale institution manages our lives through complex bureaucracy and a set of laws. Nation-states regulate social interactions. This results in local communities losing their autonomy. While the community is now producing individuals, at the same time the nation-state is destroying the community--which is now governed by a national government.
Another theory is that of globalization--or a world system. Due to the pressure of capital we are forced to move and pursue capital--in other words outsourcing. This fragments the nuclear family and also destroys communities. Through capitalization a global financial capital is produced.
Another theory is that of instrumental bureaucratization which transforms traditional communification. Things must be efficient.
Another reason or theory involves cities such as diverse interest groups, sorting and mobility and diversity.
A final reason is that of transportation--which results in cost efficiency of communication.
Here's a site that explains what a network community is.