Board Thread:Wiki Discussions/@comment-25139119-20140915033602/@comment-28861328-20140917200704

Its Hagoromo's moniker because he is the originator of the Six Paths Technique. Same as Kakashi is called "Kakashi of the Sharingan" because of his infamy for using the Sharingan. Again, Hagoromo's name was unknown to the present shinobi until he popped up and told them his name recently. Up until then, he was known only by moniker and therefore any ability, technique, descendant, tool, etc., that is attributed to him is known as "Six Paths X/Y". Every one of them. Like, literally of them are attributed to him.

To drive the point home, going off of what the other user was saying: When Madara became the Ten-Tails' jinchuriki, he said aloud, "So this is the power of the Six Paths...". Later, when Naruto is talking to Hagoromo, the Sage says, "Madara became the Ten-Tails jinchuriki in an attempt to acquire my power". The Six Paths power/chakra/whatever is his power.