Board Thread:Theories and Speculation/@comment-32457608-20170823143115/@comment-5085906-20170825161616

Ino was never trained with Tsunade and was never on Sakura's level in regards to medical proficiency. And Shizune never showed any grand feats outside of throwing needles at Kabuto. Tsunade passed it to Sakura because there had to be a way to make her at least catch up in some way to the two main protagonists. Even Kishimoto admitted that in his interview that he made Sakura Tsunade's pupil because of fan backlash towards how useless she was in Part I and then just gave up on her when there was still backlash even after he progression.

Just admit it, dude. While not entirely baseless, your theory doesn't hold up at all.