For it to make the most sense, at least in my eyes we would have had to see fatigue from fighting Naruto & Sasuke set in for Obito while Madara is essentially tireless. While Madara couldn't beat him, he would have weakened him enough to the point where either ...
Sasuke has mastered the powers of the Uchiha and also unlocked Six Paths powers. He was powerful enough to go toe-to-toe against Madara Uchiha, meaning he's much stronger than Obito. Who is stronger than Madara? Sasuke Uchihais the strongest known Uchiha to ever exist in Naruto, which mak...