By that logic he should have been able to match both of them, but they overwhelmed him with the utmost ease.
They overwhelmed him together. Look at what the weaker Juubito did. What if Madara flies up, uses Six Red Yang Formation, creates the tree spamming Juubidamas and covers himself in the Onmyoton? His Susanoo won't get past the Onmyoton, as it negates any Ninjutsu with the exception of Kamui (I don't consider the FTG seal itself as a Ninjutsu, which Obito wasn't able to remove). Don't be irritated by Naruto's seemingly superior firepower as he used 6 Bijuudama Rasenshuriken. Juubi itself also has an invinite amount of Chakra. The huge Juubidama is multiple times stronger than
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single TBB of the skinny Juubi. When you pay attention to the mountains compared to this, this single explosion already exceeds Naruto's multiple Bijuudama Rasenshuriken (at least, or above all, in height by far, so the contained energy > Naruto's TBB). And now increase the scale by multiple times for
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TBB and multiply it multiple times, as Juubi Jins can spamm them. He is free to just fly up, cover himself with Onmyoton, send out the Limbo and shot multiple Gudou Damas; maybe followed by multiple huge Juubi Damas shot in all directions, maybe after jailing Sasuke in a barrier. Sorry, I can't see Sasuke winning because he, who fought together with Naruto, had some openings against a Madara, who, on the other hand didn't nearly show the full potential of Rikudo's Senjutsu.
Obito, who had the weaker Rikudo Senjutsu, used his multiple Onmyoton-Balls, jailed the alliance in a barrier, spammed TBB with a power to destroy a country and used the Double Helix sword which was hyped to create and destroy the world, until it was broken as Obito got emotional. Juubito has shown more fire power than Naruto. You say Naruto can use TBB faster. Naruto raises his hand to create those TBB, Juubito touches the ground to instantly let a tendril with a flower appear, creating massive TBB.
All Madara did was to use some random Ninjutsu and using his last Gudoudama as a stick. Only because Madara limited himself in this fight and didn't go all out while fighting BOTH Sasuke and Naruto, who uses Rikudo's Senjutsu as well, doesn't mean that's all he is capable of. Sasuke got a powerup by Hagoromo, Juubi is Hagoromo's power as well, which became the Rikudo's Senjutsu in Madara's body, together with a Rinnegan which is also Hagoromo's power.
To put it in a nutshell, Madara is Juubito with more firepower, more speed and a Limbo. A man wielding Rikudo's Senjutsu and having his eye. While Sasuke wields Rikudo's eye only. Madara is stronger.