What's ridiculous is your lack of understanding regarding potential, you really can't see how it's plausible that Naruto and Sasuke grew as fast as they did?
Let's start with just their base birth potential:
Naruto- Son of legendary genius/ 4th Hokage, son of Jinchuriki from Uzumaki clan who possessed special chakra, and Naruto has possessed an abnormal amount of powerful chakra of his own since birth.
Sasuke- Son of the head of the Uchiha clan, and brother of another genius in Itachi. This is important to note because even within clans there exists stronger lineage, which obviously manifested in his family. Sasuke also possesses powerful chakra, that though pale in comparison to Naruto's, has noted to be quite vast in quantity.
Now let's talk about their genius because that's what they in fact are:
Naruto:
Naruto grew up with no one to help/tutor him regarding techniques, as most young shinobi do. Yet when given the opportunity to master high level techniques he without fail has. Before departing with Jiraiya, Naruto had mastered Chakra Shape Transformation(Rasengan), and he had a degree of mastery over Shadow Clone unprecedented for someone his age. This was all accomplished within a small period of training and tutelage, showing how quick Naruto could grow given the opportunity.
Sasuke:
Sasuke grew up with tutors all around him and never once squandered the opportunity, quickly earning the moniker of genius at a young age, showing he would absorb any information offered/given too him. At a point he lost all of those tutors, and still continued to progress. Before vacating the village to join Orochimaru, he grasped nature transformation, a degree of shape transformation, and was beyond proficient in every aspect of Shinobi combat.
Note: The above is important because it establishes a base for how quickly they can improve, even during tumultuous times, with little to no direct help.
Responsiveness to their years of training:
Naruto:
Naruto after returning at first glance was not that improved technique wise, which is true but only a half truth.
The only new technique he learned was essentially a bigger Rasengan, but what is important was his growth in his other techniques. After returning Naruto was the greatest Shadow Clone user to ever live, developing such skill with the technique that I believe he elevated it to an S-Rank or beyond level technique. Also he improved his skill with Rasengan, this all gave him an incredible foundation to now build from. His training with Jiraiya built up his stamina, chakra pools, and overall physical capabilities. Jiraiya helped Naruto to establish an incredible foundation for future growth while also offering up beliefs and philosophies he thought equally important to battle prowess. After returning Naruto had more life force/stamina than anyone alive, and with increased battle instincts from his already severely underrated in battle fight tactics, he was far stronger than given credit for at the time.
Sasuke:
It can be presumed that Sasuke logged much more training time as he essentially gave his life up to it. Sasuke dedicated every waking moment to training, he was not interested in bonding/spending time with Orochimaru other than training. The results showed as his growth while more surface level and apparent than Naruto's, was still greater. He grew into his body as Naruto did, while also improving every faucet of a Shinobi's arsenal. He took the knowledge of nature transformation passed on to him by Kakashi to new heights, taking full advantage of being tutored by a master of Ninjutsu in Orochimaru. Sasuke also learned to take full advantage of his Kekkei Genkai, as he had previously neglected the incredible genjustu it offered as mastery of the Sharingan progresses. Sasuke's Kenjutsu and skill with other weapons should also be noted as he has yet to be outclassed in said categories.
Note: The above shows how during training they both responded incredibly, with Naruto widening his base and future potential to unfathomable levels and Sasuke constructing upon his base to start ascending to his potential.
Use of Birthright weapons:
Naruto:
As soon as Naruto returned he made use of his otherworldly stamina and life force, during his training with Kakashi and Fukasaku he utilized his gifts to start building upon his foundation. Through the use of Kakashi's Shadow Clone training method Naruto combined his genius, mastery of Shadow Clones, and stamina to create the most powerful Wind Style Justu ever, not mention one of the strongest techniques ever. During his training with Fukasaku his enormous chakra reserves and genius enabled him to gain mastery over Senjustu. Naruto has developed a fighting style that corresponds to his abilities perfectly making him not only an immensely powerful fighter, but an intelligent one.
Sasuke:
Just as Naruto was born with incredible chakra/stamina/life force, Sasuke was born with powerful eyes and just as Naruto made use of his birthright so did Sasuke. Sasuke sharpened the abilities of his eyes and by the time he gained the Mangekyo Sharingan, he was ready to take full use of his dojutsu gifts. He gained proficiency with his eyes quickly and by the time he was near blind, he had already started combining different aspects of his Kekkei Genkai.
Use of Gained Birthright Weapons:
Naruto:
No matter how you look at it Kurama is a weapon Naruto has gained mastery over, it is the same as a summoning for him at this point, and is a summoning/weapon only he can use. Since conception and birth he has been constantly exposed to Kurama's chakra, making him the only one capable of utilizing him to full potential. Naruto's powerful chakra and life force help him resist the harsh effects of using Kurama's chakra. Minato is only able to use it due to his edo body otherwise it would just be too much for him. Naruto has tamed the Bijuu, and has gained mastery/formed a bond with the most powerful one, and now is in possession of his birthright weapon.
Sasuke:
The first weapon Sasuke was given was the curse mark, this was not a birthright weapon just one he was given, also the abilities given to him when he absorbed Orochimaru were not birthright. Though not his own power, his mastery over these spoils should be noted.
His gained birthright weapon is/are Itachi's eyes, just like Kurama for Naruto it is a weapon only Sasuke can use. By implanting Itachi's eyes into himself Sasuke gained the EMS, if anyone else did this they would just gain Itachi's regular sharingan which would be near useless. With EMS, Sasuke is elevated to incredible levels of power and without Itachi's eyes he would be blind or on to another sharingan/someone else's eyes rendering him useless/weak.
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With all of this brought into consideration coupled with their personalities, I see no logical flaw in them becoming as strong as they have. Instead of looking at them compared to other "geniuses", respect their own genius and admire that they are the true gems/successors/geniuses the Shinobi world waited for.
