Waiting to see doctor/midwife until 20 weeks

I have a sweet friend who has now had 11 babies (yes, 11. This woman is a machine). I've known her and her family since they had 7 babies.
I remember when she was pregnant with baby number 9, she didn't go to the doctor until she was 20 weeks or so. She knew she was pregnant, she didn't need someone to confirm it, she already knows how to have a healthy pregnancy, so she really had no use for a doctor until she was further along. 
This blew my mind. 
Now I'm older and thinking about having babies of my own, and doing lots of research and this is starting to make more and more sense to me.
If I know I'm pregnant, if I know how to have a healthy pregnancy, if I'm already healthy, if I've had no previous miscarriages, why would I need to see a doctor? Sure doctors can do testing early on in the pregnancy to make sure everything is normal, but even if something is wrong with the fetus, there's nothing they can do about it until I'm further along or decide to terminate the pregnancy (I wouldn't). And major problems i could have (like preeclampsia, hypertension, etc) wouldn't be a problem until later in the pregnancy anyway.
I understand it's a little bit of a different situation, this woman had had 9 babies by the time she decided to quit going to the doctor, I have had none. So maybe I'd wait until my second pregnancy to go sans doctor for the first half of the pregnancy, I don't know yet.
What are your thoughts? Can you think of other reasons to go to the doctor in the first or second trimester other than testing and oohing and ahhing over the baby? Have you made the choice to avoid the doctor until you're further along in your pregnancy?