The hygiene hypothesis is tenuous at best and dangerous (especially for immunocompromised peers!) at worst: https://publichealth.jhu.edu/2022/is-the-hygiene-hypothesis-...
"Almost no virus is protective against allergic disease or other immune diseases. In fact, infections with viruses mostly either contribute to the development of those diseases or worsen them.
The opposite is true of bacteria. There are good bacteria and there are bad bacteria. The good bacteria we call commensals. Our bodies actually have more bacterial cells than human cells. What we’ve learned over the years is that the association with family life and the environment probably has more to do with the microbiome. So one thing I would say is sanitizing every surface in your home to an extreme is probably not a good thing. Our research team showed in animals that sterile environments don’t allow the immune system to develop at all. We don’t want that."
There’s also a concept of immunity debt, although that’s more of an explanation for certain diseases being especially bad the year following COVID restrictions than an argument for exposure.
But sure, let's just call the hygiene hypothesis tenuous.
I mean, many populations have more/less risk of many physiological things. That's just how it goes.
Black men are at much higher risk of prostate cancer. White people of melanoma. As a man, I pretty much don't have to worry about autoimmune disorders because my risk is 1/10th that of a woman's. But, my risk of heart disease is much higher - even at the same weight!