Kishi stated that Sakura is an ordinary girl, she does not derive from a special clan...
Her parents are fodder, and just because she is supposedly a main character along with Sasuke and Naruto does not mean that she is going to have some kind of off relation to the Sage...
Personally, if Sakura had credit to being of Hagoromo's brothers' bloodline, then that would downplay her abilities even more.... Just like Naruto and Sasuke being reincarnates of Ashura and Indra downplayed their abilities.... Giving people an excuse saying " They are only powerful because they are destined for it."
Just take the fact that Sakura is not special like Naruto and Lord Sasuke.. TY