...and admitting that you know it exists is grounds for you not being allowed on a jury.

But yeah, judges judge the law, juries judge the facts. so the judge can corral how the trial proceeds and explain to the jury what criteria they are supposed to be following and what evidence they are supposed to consider but the jury can decide what it wants and their decision cannot be challenged - which means if they decide that someone is guilty/not guilty for reasons wholly unrelated to what the law actually says then that's what it is.

It's why I was surprised that Trump was found guilty on all counts in the NY trial - I was expecting a mistrial due to hung jury before the trial even started because I was expecting at least one hardcore supporter/opponent of Trump who was going to vote based on that regardless of the evidence making it impossible to have a unanimous agreement.