Another problem with discipline is that half of children live in a home with no father in it, or perhaps only visit their father two weekends a month. Two parents (one of each gender) in a stable household is the superior "alternative".
My child spent half of her childhood with only me in the home. She was also the best behaved child on our block. And all the other kids came from two-parent homes. An only parent, even a mother, CAN effectively parent and discipline. And I had a very difficult child.