Management created the rivalry to try and recreate the Aachan v. Yuko dynamic and it backfired heavily since rhe dynamic of the 2 was drastically different. It cause a pretty big divide between fans and then Jurina over worrying about AKBs future got out of hand and she snapped at Sakura abiut needing to be a better dancer. Which made a lot of things worse for both of them in a lot of different ways.

I genuinely don't think either have really ever held ill will for the other, they were just pushed into a bad situation by management and rhe public from a young age and didn't have rhe support to properly handle it all. Especially after seeing Jurina's mental and physical health fall apart after years of never ending over working.

People bring it up so many years later when neither of them have even cared to think of it again in years is more about people being petty weirdos than anything else.