I disagree with your statement that a single (intentional) mother can model ideal female behavior-—wrong. She is modeling selfish, immature behavior.
The reason both men and women are needed as parent role models is for the intimate observation that family life offers—a look into the interaction between male and females where children can figure out the differences and similarities of the TWO sexes-—what is a good male—what is a good female? They need to learn what is normal and not—they need Virtue modeled so they will become Virtuous.
Girls who do not have a loving father figure will be promiscuous and always searching for males to give her that nurture and love that wasn’t there when she was young. It doesn’t matter that she had a lone female to model herself after. Children need a loving mother and a loving father to learn how to live a full and meaningful life.
This is necessary for basic long term future mature relationship with the opposite sex. Their young world has to have healthy male and female role models so they can deal with all human beings and be comfortable with both sexes. It is the ideal.
I was not referring to the women who deliberately get themselves pregnant, but to the women who are forced to raise their kids alone--the widows and unwilling divorcees. Many a man (like Abraham Lincoln) will speak or write with reverence about the noble spirit of his lonely mother. My point was that no matter how wonderful a mother is, she can't be a father.
In a divorce, both parents are selfish. Divorce is a trainwreck for the kids.
And for Father's Day, a bit of wisdom:
"The greatest thing a father can do for his kids is to love their mother."