I am new to this forum, but thought I'd introduce myself. I have three children, the last one was born unassisted at home a month ago. His birth was my favorite so far. My first child was born in a hospital with a doctor with lots of interventions, the second one at a birth center with a midwife and this last one at home.
I think giving birth unassisted is incredibly empowering. As long as you are healthy and take care of yourself your body will take care of the baby. After all, your baby grows all by itself in the uterus without your interference. Seeing a doctor or a midwife won't guarantee you are healthy just as going to the dentist regularly won't guarantee you don't get cavities.
That said, for first-time mothers an unassisted birth would be a huge step. I was certainly not in that place at the time since we didn't even plan to have the baby. The medical approach to childbirth is very much fear-based and scares people into submission, because they think the baby can only be taken care of properly by a doctor in a hospital. Most complications are rare especially if you are healthy. But giving birth unassisted means you have to take responsibility for yourself and your child which most people won't do for childbirth even though they do it on any other occasion.