The fundamental element of social networks is an open network.
And to sustain it,
you need a way to make money to maintain
this unprofitable free service,
and to make money without eroding the perception of being free,
you need very sophisticated targeted marketing,
and to increase that sophistication,
you need users to voluntarily register, update, and continuously maintain their own information.
This is exactly where the roles of Twitter and Facebook diverge.
And one issue we must not forget is that
social networks like these
are not just about problems arising from the service itself,
but are continuously forcing us to ask fundamental (somewhat philosophical, identity-related) questions
about humanity and innate human relationships.
For example,
(I don't think you can build connections or fill real-life emptiness through Facebook. I believe human relationships should be advanced with distance and time. What's needed to build trust is opening yourself up and time. Whether relationships on Facebook become a hollow house of cards or become friendships that transcend time and space is ultimately up to you. In my case, I have no school, regional, or family connections on Facebook - it helps me maintain relationships with friends I met abroad.)
Just as drinking buddies or mandatory drinks with bosses can't enrich your life more than family...
Facebook can't grow your thinking more than your grandfather's heartfelt advice.
