Except that's just it genius-Hagaromo NEVER took the chakra he gave Naruto/Sasuke back. That's the critical point that you're misunderstanding, and that is leading to all the fallacies that you are sprouting. Losing the seals and their abilities =/= losing their 50% of non jin Hagaromo's chakra that they received. How else could Naruto use the six paths sage mode? How else could Sasuke use the Rinnegan effectively? In fact, leaving all of the above behind, let's look at this simply. You read the Naruto/Sasuke fight, didn't you? So you know how strong they became. Do you honestly think, that Naruto and Sasuke, WITHOUT Rikudo chakra, could pull off what they ended up doing? It makes zero sense. Sasuke's enhanced PS chidori, Naruto's new enhanced avatar would all be impossible without Rikudo's chakra fuelling not only the power of their techniques, but their chakra reserves.
The yang seal was one of the seals needed to perform the Six Paths Chibaku Tensei. Nothing more, nothing else. There's ZERO evidence on your part, that the seals literally contained 50% of Hagaromo's chakra, and that Naruto/Sasuke lost all of it after after the seals were taken back.