RSM is Six Paths chakra, which Ashura had that. Hagoromo himself attested to that. Naruto had Six Paths Senjutsu And he didn’t obtain the Rinnegan.
@bold: Who were you talking about there; Obito, Indra, Ashura or Madara?
No, RSM is Six Paths Sage Mode and knowledge bestowed upon an individual with a righteous heart and a courage soul, by Hagoromo himself. I paraphrased a tad but the message is still the same; Hagoromo tells Sasuke that he “entrusted Ashura, alone, with his powers but this time I split them between the two of you.” Also no, RSM can be amplified with the power of the Bijuu but it isn’t dependent on it and therefore, RSM isn’t the collection of the tailed beasts. In regards to logic of how Indra and Ashura managed to transmigrated their chakra for centuries, it isn’t explained. BUT as I described in the OP, it has to do with Six Paths chakra.
@Underlined: To be honest, I have no idea what you’re trying to argue here but... the difference is that Madara was smart enough to obtain Rikudou chakra on his own (Rinnegan awakening) and become the Juubi Jinchuriki- which granted Rikudou Senjutsu to accompany Madara’s own Rikudou chakra. Another difference is that Madara didn’t get OP handouts from the god of shinobi, Madara’s Rikudou chakra wasn’t Hagoromo tier Rikudou chakra. For one, Madara only received a trivial portion of Hashirama’s chakra. And two, Hagoromo’s chakra could utilize Six Paths Senjutsu while Madara couldn’t even utilize standard Senjutsu. Also, Obito explicitly took some of Madara’s Six Path Senjutsu (which was granted to him by being the Juubi Jinchuriki). >And anyway, Naruto had Six Paths Senjutsu and was an Ashura reincarnate and he didn’t awaken the Rinnegan, and Sasuke awakened it in one eye simply because Hagoromo forced his eye to evolve. Ashura himself was gifted Six Paths chakra and didn’t awaken the Rinnegan either. Whether Indra’s doujutsu evolved prior to his death isn’t explained but regardless of Indra not obtaining the Rinnegan, he still had Six Paths Chakra. <