Facebook doesn’t make the comments that will kill people
"Facebook is a communication tool for friends and family that is sometimes used for illegal activity" is categorically different than "Silk Road is a tool created to facilitate illegal activity."
Probably the first social media genocide was organized on Facebook, the Rohingya genocide. https://en.wikipedia.org/wiki/Rohingya_genocide
Similarly, the first social media revolutions were also organized on Facebook (and Twitter): https://en.wikipedia.org/wiki/Arab_Spring