I'm not sure entirely what Kishimoto intended for the Yamata no Jutsu
This definitely feels like Orochimaru's counterpart to Jiraiya's imperfect Sage Mode. We know dragons in Naruto are heavily associated with snakes, being superior to them. Kabuto even claims his perfected sage mode allows him to become a dragon from a snake.
So I would not be surprised if the Yamata no jutsu is Orochimaru's method of using senjutsu chakra beyond the curse mark.