Board Thread:Theories and Speculation/@comment-5413572-20150114180437/@comment-1512913-20150221083207

The databook says that giving birth to Hagoromo and Hamura made Kaguya's chakra disperse to them, people interpret this like them simply inheriting it, thus chakra being spread from one to others, rather than her having lost a piece of power, but if that were the case, there would be no reason making such a mention at all, since it's logical (would be like stating that children inherit their parents' genes), so I interpret it literary and doing so in fact could explain her lack of Tenseigan and Rinnegan powers.

So I find it obvious, that the chakra stripped from her doesn't consist only of 1-9 Tailed Beasts, but also of chakras of Hagoromo and Hamura + everyone to whom the two spread their chakras, hence why Kaguya wants to sucks everyone dry, she wants to be complete again.