Regardless of the technical rules about how confessions should be treated, a jury will always overvalue a confession. The same applies to eyewitness testimony, which is basically useless but juries accept it as undeniable truth.
The game of prosecution is not "prove the accused is guilty". The game is "convince these random people that the accused is guilty". The later is a decent approximation of the former but I wish we had something better.
Regardless of the technical rules about how confessions should be treated, a jury will always overvalue a confession. The same applies to eyewitness testimony, which is basically useless but juries accept it as undeniable truth.
The game of prosecution is not "prove the accused is guilty". The game is "convince these random people that the accused is guilty". The later is a decent approximation of the former but I wish we had something better.