Even further than that. It's Tobirama's fault for not appropriately disposing Madara's body as well as fueling the hatred of the Uchihas.
Without Madara Black Zetsu wouldn't have anyone powerful enough to turn to or anyone with a Rinnegan for that matter. Nagato would have been offed when they were attacked by Hanzo or sooner and that would have been the end of Akatsuki, and Obito would have died from his injuries. The plan to reawaken the Juubi or IT plan would have ceased and the destruction of Konoha would have been prevented. Furthermore, Tobirama created Edo Tensei and not only did it brought forth the War along with bringing back Madara, it reawakened Kaguya.