This is not new, the “cleanliness theory”.
Read a article a while ago where it was suggested that the more affluent societies, who can afford to be cleaner, in the end starts having more ailments that do not seem to be present in the poorer societies.
Years ago read another article where they found that common allergies where skyrocketing in kids in I think New York, if memory serves. The kids where growing up with no regular contact with soil, living in concrete jungles. Their immune systems where underdeveloped.
Very recently saw an article that pointed out why natural birth gives that baby as an adult, a stronger immunity system than a clean cesarean section. As gross as this is, it is natural, in that fecal matter and other bacteria enters the baby’s eyes, nose, mouth, which in turn triggers the immune system.
Also an article about the cleaner your skin is kept, the worse off the good bacteria in your gut gets. Somehow the two are linked.
Even some cancers are being linked to being too clean. Being clean is good, being too clean is not good at all.
And then you have the entire food chain messed up with antibiotics and pesticides, appearing in foods all over.