Yeah but even before that they were powerful enough. Madara needed to steal Hashirama cells to be stronger. Basically all of his powers after he got edo tenshoed were stolen powers. He cheated death to get stronger.
Ok, I'll explain this in more detail. Madara is a powerful character, we all know that, but his power<Naruto and Sasuke. By feats, Naruto and Sasuke are clearly stronger, and saying that Madara has more powerful usages of an ability is merely baseless asumptions.
First off, Juubi Jin Madara has inferior reflexes(and presumably senjutsu in general) than Naruto as seen in the databook, which had the caption to what we'd call the new "base Naruto."
Let's look at Madara's feat.
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Madara using planetary devastation, the most powerful rinnegan ability, made multiple huge meteors by fragmenting a huge planetary devastation. This scales Madara's Deva Path to very high levels. Also, it's quite reasonable to think that Madara could have kept the huge CT core and used it to make a huge meteor.
That's fine and dandy, but we have this.
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Sasuke's PS had the capability to bisect a meteor with a single slash, and used successive slashes to reduce it even more. Naruto's Tails=this capability.
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Bear in mind, Naruto can make TBBs.
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Take into consideration that Naruto and Sasuke's avatar and PS attributes> CT fragments and the huge difference from physical attributes and a TBB, and shadow clones, Madara would be in deep trouble if either starts off fresh with their skills.
Also, considering the even more massive difference their final forms had to PS and Kurama Avatar, that's one-shot the largest CT level, or flat-out completely obliterating Madara. Should I even show you the scale of the explosion from their ultimate attacks?