When a child misbehaves why does the parent often blame the person being mistreated instead of their own child?

The parent who sticks up for the child who misbehaves has very poor parenting skills. Generally, their child misbehaves more on average than children of parents who are more active in teaching social skills and respect for others. The ineffective parent blames the victim for different reasons. Good parenting takes time and effort. Poor parenting is often a result of parents who are more concerned with their own needs or just plain laziness. Typically the parent is in denial of the fact that their child is a trouble maker or bully who lacks social skills and doesn't play well with others. Also, that type of parent is trying to hide from the reality that they are not doing a good job of raising their child.