This assumes the jury is rational and objective. There's plenty of behavioral psychology that goes against this, but a more glaring observation is that lawyers do not seek to maximize the objectivity of the jury during selection. It's usually very much the opposite.

The goal of the district/trial court system is finding of fact. That's objective. Winning is about swaying the jury, which pulls on the levers of subjectivity. The system is, in part, designed to protect the rights of the innocent. Take the Blackstone ratio, which assumes it is better to let 10 guilty people go than convict 1 innocent. Verdicts cannot be purely objective in a system designed to be asymmetrical.