She started to successfully developed a S-Rank at the age of 13. Something a grown woman like Shizune couldn't do. Hell, Shizune doesn't even have chakra enhanced strength. It may not be a KKG, but she is gifted.
Not from her brother, father, friend or the sage. Her gifts are inherent talent and I already said it. I am not sure what point you are trying to make here. Sounds like you are finally accepting her talent. 'Fine by me ^^.
And Itachi was an ANBU Captain/Triple Agent for an S-rank organisation led by 'Madara', Danzo 'the Darkness of Shinbi and the Konoha Elders and his Clan... the latter of which, he slaughtered.
So? Sakura is not the genius of the century is she? Besides Itachi had sharingan to boost his powers and his clan KG and jutsus. Plus he was born during war time and grew up seeing too much violence and his family is one of the leading families in Konoha.
Sakura is born during time of peace, in an ordinary family. She doesn't have that kind of motivation from early on as Itachi, to be something more than she was- not till her own experience with life drives her to strive for more. She was still doing her best and studied the book thoroughly and practice enough to be able to have a fine chakra control.
Kakashi - at thirteen - was a jonin and fought in the 3rd Shinobi War. He developed the Chidori.
Again a renowned father ( better training in childhood) + got a sharingan gifted to him. And war- funny you would mention that as if ending up in a war situation was a personal accomplishment... He didn't succeed that much is war did he? Despite his gifts- Obito "died" ( supposedly) saving him and Rin ended up dead. Minato gets blame for being busy with other missions and not being able to help them out.
Really no idea why anyone would make such arguments seeing the manga is mainly about a lot of awesome guys being shonnen and all.
Naruto - at twelve - knocked out Hizuren Sarutobi with the Sexy-no-Justu and was capable of using (a version) of Rasengan - a notable feat in itself due to his piss-poor chakra control.
Because he was taught. And you have poor understanding of what poor chakra control meant- Kakashi said Naruto wasted too much chakra in doing the same thing, Sakura wasted almost nothing. Sasuke was in between he wasted much less chakra than Naruto but more than Sakura if all three performed the same tech. Naruto had too much to spare so he succeeded despite poor control back then. Plus you seem to forget he was TAUGHT that tech by his godfather. Sakura was neglected completely during that time.
Sasuke - mastered his Sharingan and Chidori.
Good for him. Finally since he had the b asic requirements thanks to his KG and teacher. You are seemingly writing a lot but irrelevant things in here... what's your point ?
The Rookie 9 - mastered team work; a concept in which largely evades Sakura right up into the 4th Shinobi War.
Wow- you have to have a team first you know? I didn't think I would find more absurd and illogical argument to bash someone. The original team seven never fought as a team till finale because Sasuke wanted to play the lone wolf and saw her as a medic in the back only. Naruto too was away most of the time and not really practicing coordination in a fight with her. Sai's contribution as a team mate was putting her on a gilt trip when she was already torn because of her feelings for Sasuke who was going down the path of darkness rapidly and defending him against the interest of the village was getting more and more difficult.
Just because Shizune couldn't master that technique, doesn't mean it would be impossible for others to do so. Beating Sh*tzune isn't exactly the pinnacle of achievements.
... That's why we see the medics with bayakugo summoning slug all over the field. ..Wait there are only 2 such people.
As for Shizune was not motivated enough and kind of got satisfied with what she learned. Sakura on the other hand asks Yamato too to teach her the justu which he used to calm Naruto when he went berserk in bijju mode. Though he said it was not possible since it required Senju cells.
Sakura despite her fairly normal back ground didn't just sit in the background saying "what can I do -one of my team is a jinchuriki and another Uchiha prodigiy" So I will just lend moral support and prey daily that they return safely. "
The technique itself - requires precise chakra contorl - big f'ing whoop. It's an S-rank technique that allows her to catch up, somewhat, to her team mates in terms of chakra reserves and durability.
Such hate ..
... not that she equals them, even then.
She is a master in her field and that takes her right up there. Also she posses the qualification to handle herself in such a team where every single remaining member is dealing with personal issues and be there for them if they would let her. Hers was a slightly flawed character and that of a normal girl who had little idea about who the people she ended up really were. And she comes to know them and that not only makes a difference in her outlook towards them , she changes herself too be able to keep up. She gets ample growth as her life experience increases.
Her character clearly suffered- ( frankly Naruto and Sasuke's too to an extent- All three main characters retained some annoying traits for far too long which if resolved earlier would have increased their personal likability).
Even the side villains get so much development that's rare in most mangas -most either do not add so many or keep it short and avoid making them too complicated. The writer has hard time forgetting his villains and wants a closer for every little damn thing out there. So they steal a lot of time and attention away. They get to be interesting but at the cost of the main cast. So there are both plus and minus side to it. Sakura got the worst hit among three due to that trend as she was not the focus of the story and not even the girl meant for the hero. But her performance was not that bad to warrant such hate as a character.