"Foreign organizations have also found private groups useful. Last month, when Facebook took down hundreds of public pages that it said were connected to a coordinated influence operation with hints of Russian and Iranian involvement, it also removed three private groups. The company did not name the groups or say how they were used, but it revealed that 2,300 users joined at least one of them.Fringe Figures Find Refuge in Facebook’s Private Groups-- NYT
“The vast majority of groups on Facebook are probably the run-of-the-mill groups,” said Renée DiResta, a researcher with Data for Democracy who studies online extremism. “The challenge is, how does the groups feature interact with the other features on Facebook that we know are causing radicalization, hate speech and genocide in certain places? Who is taking responsibility for looking at the negative externalities of this push to create communities?”"