Because dads don't always think like moms.
Another key skill a Dad should possess is to help children identify their mistakes themselves, without rubbing it in or making them self-conscious.
Correct Your Child’s Speech Sensibly
It may not always be all right to point out the mistakes your child makes while speaking. A better way to do this is by repeating what your child said, with the correction, as if the conversation is normal. Pointing out mistakes could make your child self-conscious and less open to conversation for fear of making a mistake.