No so much a single historical fact, but people tend to fall for fallacies of nature, and imply that we should go back to the way we did things “naturally”
But often times, this idea is extremely historically inaccurate. Many times, the way we did things “naturally” resulted in a lot of, you know. Death.
For example, “giving birth naturally.” Some people seem to think that before modern obstetrics, that we were all just a bunch of natural goddesses giving birth in the forest. But the reality was a lot more grotesque than that. If everyone gave birth the way we did in 1900, we would be seeing a lot more childbirth related death. We would also see a lot more women dealing with fistulas, and being ostracized
Same with vaccines. Letting “nature” take its course, killed us, sometimes at alarming rates (like with smallpox). Oh sure, they had natural immunity to a lot of things, just like we develop natural immunity to a lot of things - except some immunities are a lot safer to get naturally. You don’t just develop natural immunity to polio, you have to get polio and suffer the permanent *natural* consequences. But people have this idea that everyone used to walk around with better immune systems and they would drink elderberry