Right on the point

That's exactly what I've been thinking. It's more about what we eliminate from diet than what we do eat.

Different people have different degrees of susceptibility to the damaging effects of the modern Western diet. This depends on genetic background, age, activity level and many other factors. When you remove damaging foods, peoples' metabolisms normalize, and most of the differences in health that were apparent under adverse conditions disappear. I believe our genetic differences apply more to how we react to adverse conditions than how we function optimally. The fundamental workings of our metabolisms are very similar, having been forged mostly in hunter-gatherer times. We're all the same species after all.