Hi Cody, great question.
The reasoning behind that remark about Agrarian humans experiencing better health is about the traditional foodway practices that enhanced nutrient bioavailability and absorption through soaking and fermenting grains and legumes, thus removing anti-nutrients and toxins. While many people and cultures still practice these traditional foodways, it is not as common as it once was in Western culture, where many grains are processed, refined, and chemicals/preservatives are added for shelf-life.
The Neolithic Revolution (Neolithic Revolution (12,000 B.C.–3,000 B.C.) ended as societies and cities were built due to its innovations. It led the way to the Bronze and Iron Ages, when humans discovered how to work with metals to create more advanced tools for war, farming, art, and trade was established. I understand your question, as many of the innovations from the Neolithic Revolution (agriculture, farming, and settlements with larger populations) are present in today’s society. Among many differences, with all of the advancements in technologies, we don’t need to live near our farms to sustain ourselves, as we can simply walk to the grocery store and buy produce that has been grown and shipped from all over the world. We don’t have to grow our own food to support ourselves and our communities to survive, whereas humans during the Neolithic Revolution did.