What the manga deems matters not in the light of facts.what's there to "brew up"? You say that as if it somehow changes what the manga deemed to be the most likely outcome if that fight between Rikudou Madara and Naruto & Sasuke kept going.
The manga deemed that Kaguya would be the hardest opponent they've ever faced, yet Naruto for 90% of the match solo'd her mid diff. Fact is Naruto could've solo'd high/extreme diff.