I was a single parent due to a horrible and necessary divorce. I raised two children alone, right from the start. It is impossible (almost) to be mother and father to children, as well as the sole financial, educational, emotional, spiritual, etcetcetc support. The children absolutely feel that something is missing with only one parent. Raising children is a two parent job. Some people manage fine, most don't. If there is a supportive extended family, even better. I didn't have that.
If someone is a single parent due to widowhood, it is totally different. They know Daddy (or Mommy) is not there because he can't be, not because he doesn't give a shit.
But don't you think that a single mother by choice brings a child into this world knowingly, and lovingly? What is worse, not knowing your father, or knowing you have a father who doesn't give a sh!t? My father only wanted me to avoid child support. He didn't give a crap about me whatsoever. And that hurt a lot. I would have rather not known anything about my father.