First, let me offer this disclaimer: Nothing in this article should be taken as medical advice. I am a doula – not a nurse or doctor. While I have studied pregnancy and birth extensively and provide evidence-based information only, I speak in generalizations and from anecdotal experience.
Each pregnancy, labor and delivery is different, and there are exceptions to every rule. If you have questions about your specific situation, I’m happy to point you toward birth resources, but I strongly suggest that you consult with your own health provider.
Phew! Got that out of the way! Now on to the good stuff ...
Undeniably, women have been giving birth since the beginning of humankind. It is only in the last 150-ish years that birth has been considered something that requires medical intervention.
For generations upon generations, birth was simply a fact of life — a biological process and a nearly inevitable rite of passage. Pregnancy was natural, and generally not interfered with.
That’s not to say this was always the best thing for women and infants. Women frequently died in childbirth for a variety of reasons, ranging from poor prior health to medical professionals who didn’t wash their hands. 
Modern medicine has incredible benefits, and has saved the lives of many who experience high-risk or complicated births. Still, the U.S. maternal mortality rate is absurdly high compared to other developed nations, and not because of out-of-the ordinary situations or rare conditions.
The American College of Obstetricians and Gynecologists has put out several statements warning about the risk of elective or unnecessary cesarean sections and other medical interventions.
ACOG states that "although cesarean delivery can be life-saving for the fetus, the mother, or both in certain cases [...] it is important for health care providers to understand the short-term and long-term tradeoffs between cesarean and vaginal delivery, as well as the safe and appropriate opportunities to prevent overuse of cesarean delivery".