What a silly topic, of course Kaguya lost and its not because of power, she didn't lack anything in that department. It was her skill, to put it mildly she sucked. Chakra can't be "lost" you misinterpret what she was meaning, it wasn't a literal statement of "that's my chakra" it was a declaration of ownership of ALL chakra regardless of where it came from. Her strength comes from the combined tailed beasts by no means was her power reduced by breeding. The only direct chakra she perhaps ever lost was when Hagaromo and Hamura were born from her, and even that is arguable. The rest was used to create the tailed beasts, she was as strong now as she was back then.
Take what Naruto said during their battle, she knew nothing of the history of ninja. Aka what he was meaning wasn't just the fact she didn't know of their troubles or trials, she had no idea what she was up against. Her mind was dull and her skills weak, she was up against two of the strongest most skilled ninja of the era.
Its no surprise that they ate her alive even with all her power, she simply had no idea how to use it. An untrained princess with all the power of the world....impressive but still an untrained civilian with immense power. Against two finely tuned warriors even with weaker powers she was simply out classed, she also lacked the will to win.
I don't even.
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Databook.
"Ninshu, the power that linked individuals, became obsolete. Mankind, endowed with Kaguya's dispersed chakra, brought back the turbulent times and wielded ninjutsu as a weapon..."
From the moment they assumed humanoid form, mankind had walked a world of strife waging war against one another. The ground was stained with blood, and as if drinking it in, the Divine Tree took root in the earth. In time, the Divine Tree bore a single fruit, and a clan migrated from another world in search of it. They were the Otsutsuki clan. Kaguya, leader of the Otsutsuki, ate the Divine Tree's fruit and became the originator of chakra, and with that tremendous power subdued the world in the blink of an eye.
Ohtsutsuki Kaguya had brought an end to the turbulent times. Dubbed the Rabbit Goddess, she received the blessings of the people and gave birth to twins.
↓ The birth of Hagoromo and Hamura. Kaguya's chakra had become dispersed.
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Kaguya's desire eventually turned on Hagoromo and Hamura, her own twin sons with whom she had split her chakra. Kaguya formed a plan, and in order to take in all chakra, fused with the Shinju and battled against her twin sons.
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Manga scan states Hagoromo's chakra is her's, and the next that Hagoromo spread it through the world via Ninshu.
Don't know about you but both the Manga and Databook are clear about this.
She still didn't have all of her power and the world's chakra is her power.