Academic Societies on Facebook- Why?

One of my academic societies, namely the College on Problems of Drug Dependence, has a Facebook group page. At present there are over 100 people* following the group with nothing happening. Maybe about three posts on the wall.
This brings up the obvious question.
What role can a Facebook group possibly play in the function of academic / scientific societies?
I realize this is part and parcel of some larger questions about the role various so-called Web2.0 functions and features can play in the conduct of science as we go forward.
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* my failure to recognize many names suggests to me that this is primarily an exercise for trainees at the moment.

I am…

I am a friend. A friend to women who I met when I was 5 years old, ones I met in high school, college, grad school. Women I met as a postdoc, as a faculty member, as an inhabitant of my community. They work in any number of professions from publication to politics to public health to scientific research to mainstream media to education, etc, etc. Many different walks of life. Many of them experience uncomfortable moments, sustained toxic work environments and/or flagrant discrimination in their working lives. I like my friends. Their continued happiness and well being is important to me.