Board Thread:Naruto Discussions/@comment-26488946-20150630094329/@comment-5407586-20150630141606

Thekillman wrote: The chakra of Hagoromo is present in the from of the Sharingan and the Sage body (e.g. Senju/Uzumaki). Mixing that should be enough. However, it's likely that even when the conditions are met, the rinnegan is still rare.

Consider this: The Mangekyo Sharingan is awakened by watching someone close die. We've had several Ninja Wars and even the Warring States period where hundreds if not thousands of Uchiha fought and watched people close to them die. Yet, Madara and his brother were the first to awaken this power. Sasuke and Madara only awakened the rinnegan, both with the Mangekyo. Obito had the conditions but did not awaken a rinnegan. So clearly its not an easy thing to get the Rinnegan. The Rinnegan is undoubtedly rare. Only two shinobi after Hagoromo could manifest it.

And, about Madara and Izuna being the first ones to awaken the Mangekyō, it's wrong. Maybe Madara was the first to gain the Eternal Mangekyō Sharingan, but that's it.

Obito didn't fulfill the conditions required to awaken the Rinnegan: he had only Hashirama-imbued Zetsu cells, which gave him a portion of Asura's power, but he didn't have the chakra of Indra's trasmigrant, at least not to our knowledge.