Side lines or not, she was very useful, unlike what you said.
jajajjajaa I can't believe your saying this, It's not even funny if you admit you think every single Sakura feat it's a plot hole, It's like you admitted how biased you are.
Either you don't know or you are playing dumb, or ignorant about how Byakugou works, and ignoring the fact that Sakura confirmed with Gaara why Medical Ninjutsu wasn't working, CPR was both the only way she found and the only thing Sakura could do with the little chakra she had left.
Re read the 4th Databook, the manga, whatever. I am not explaining it to you if you are only capable to understand when it serves you.
Either lack of skill or lack of neurons.