Radical suggestion: People are responsible for the actions they take, and not the actions of others. If I pick up a machete and begin lopping limbs off Canadians, that's my bad, not Facebook's.
It's possible to consider violence to be a contagious disease, however. Under that kind of lens, information platforms and communication tools could be seen as a transmission vector. It's hard to figure out what improvements could be if that's true; either way, it's another perspective.
[1] - https://www.ted.com/talks/gary_slutkin_let_s_treat_violence_...