Basically Facebook were the equivalent of radio stations in Rwanda. The difference being if facebook had assigned adequate resources, they could have removed egregious content.
Would that have stopped the killings? It might have slowed down the spread of rage.
Or it could have furthered censorship and propaganda. It's easy to sit on your hands and think the status quo is fine in Rwanda if every bit of footage revealing how bad it was is suppressed.
Radio is a tool, used to terrible effectiveness by several groups to further their aims. Rwanda was and is _horrific_. > 3/4million people died. So was Bosnia, Timor, Lebanon.
You can't go from 0-100% genocide without a concerted effort.
Should facebook have done more? you fucking betcha. Are they guilty of fanning the flames? totally.
are they responsible for the genocide? no. That is very much down to the military junta, aided by Aung san suu kyi.
Would that have stopped the killings? It might have slowed down the spread of rage.