If we blame Rin we might as well blame the Hidden Mist for forcing her to become a Jinchuuriki. However, I'm going to blame Obito for removing the Nine-Tails from Kushina and controlling it to destroy the village. Though, Obito lost control and the Nine-Tails consciously killed Minato and Kushina himself.Well, Rin kinda killed herself (she put herself infront of kakashi) so rin is the one who set off the chain of events?