Board Thread:Theories and Speculation/@comment-26389094-20150918090852/@comment-5407586-20150918120032

Madara stated that those who possess the power of the Samsara and got close to the Moon could open the Rinne Sharingan to start the Infinite Tsukuyomi. Obito had one Rinnegan of a set of two. Maybe if it were Sasuke's unique Rinnegan it could've worked. And consider also that Obito became the Ten-Tails' jinchūriki when the beast had yet to fully "mature", due to it possessing only little fragments of the Eight and Nine-Tails' chakras.