Wait Kaguya Third eye can use the powers of everyone in infinite tsukuyomi.

[SpoilerAlerts]

Just reading this scan if this was true Madara with third eye power was on a totally different level when it was closed I mean he access to Hachimon I'm pretty sure he would have used it and with immortality he can't die from 8th gate.

He could have amp his power 100 times his current power.

This is probably what naruto mean she didn't know or see this justu before. The third eye can use all justu from people in infinite tsukuyomi.

Spoiler

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[Gein]

i dont know im really high

 

[Your Creepy Stalker]

You know,

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is what you are talking about.

 

[Angelic.]

she absorbs their chakra

 

[Seventh Sama]

What it meant by that is their chakra. Absorbing someones chakra doesn't grant you their powers.