From my understand and for watching Naruto for over a decade already. The whole show was leading up to this "Ultimate Showdown". Uzumaki clan VS Uchiha clan to determine witch of the two are the strongest of the clan. Naruto and Sasuke are the reincarnation of the "Sage of the Six Paths" two son. And, Madara was just a puppet being playing by Kaguyas "Will" "The Black Zetsu". The Great Ninja War was the pinnacle and platform for Naruto and Sasuke full potential. Their power alone is on par with "The sage of the Six paths". The irony in all of this is no matter how strong you try to become, even if you far surpass your colleges and comrades. You can't never prevail with out your own support system. Naruto and Sasuke were each other's support system and they rival each other to the point they almost lost they lives "Twice". Madara had his own fate and always thought his way was the only way in the ninja world. Strength and power clouded his judgement to what was really being played in front of him. Madara greed took the best of him. And thats why he lost to Naruto and Sasuke. Any opinions on how the outcome of the ninja war would had been if Madara was able to kill Kaguya? And, if Naruto and Sasuke were not able to beat Madara even with the power of the Six paths. Who would had been able to defeat Madara?