I've had my share of bad experiencing regarding behavior scores, and I really think behavior should be completely separated with academics.
First of all, when a student has a final score of 90 on math in their final report, what do people think of it? They would think that this student has good mastery of the subject math, and not that they behave well in math class. If you were to make behavior affect this final score, would it still reflect the mastery of the given subject? I think it is really unfair to the students who master the subject better, because their scores do not completely reflect their academic capabilities anymore.
Second, scoring behavior of a student itself can be extremely biased. Each teacher would have their own standards of what gives good marks in behavior. I've even seen some teachers never giving their students full marks on behavior because 'nobody is perfect'. Then take in favoritism into the equation and this behavior score becomes even more biased.
Teachers might subconsciously (some even consciously) give better behavior scores to students who they are closer with. In this case, scores wouldn't be a reliable method of measuring a person's abilities anymore. This makes behavior scores not standardized, which is the opposite of what scores should be.
Last but not least, how flawless of a person are you to judge a person's character? Can you even say for sure this is their real behavior and not just a mask? I've seen many students act polite in class, but straight rubbish among their friends and parents. What's the point of the behavior score at this point if it doesn't even judge their true behavior? You would be scoring how good their appear in front of others/how good they are at deceiving people about how they look, instead of their genuine behavior.
I've seen this policy/rule sabotage bright students that are genuinely good at their studies, just because teachers don't see their effort. Teachers can only observe them at school, and yet they judge and give scores on their behavior, affecting one of the few things they can genuinely and honestly measure, which is academics. Even worse, a second, hidden purpose I've seen some teachers/principals imply of this behavior score is to help students that are struggling with their scores, so that just by showing good effort, their scores would be helped up.
What do you guys think of behavior scores?
edit: to add context here, this system is implemented in indonesia, and i just wanted your opinions about this. therfore, it might be abit different to the systems you guys would use in your countries.