We shouldn't generalize. We can have different opinions about Facebook, but this all is about how Facebook can help a community to grow.
If you are Italian, try to follow Italian Startup Scene for a while, and try to feel how high is the quality on it.
About 'building something', I can assure that it's the true spirit of the group, that's focused on doing things, much better than spending time to discuss ;)
The level of Facebook addiction in this country is really scary. I see fellow engineers constantly on Facebook during free time, instead of actually building something.
Sad, really.