> a diet lower in fibre and higher in protein, fat, and sugar can equally be found in China and Indonesia
On what basis have you arrived to those conclusions? The normal diet in China and Indonesia is plant based. Yes, they eat a lot of rice, but that rice is much more healthy than the vitamin-fortified substance made out of bleached, white flour that we call bread nowadays.
And don't mistake the food that you can eat in your local Chinese restaurant to what the Chinese are actually eating. For example much of the food promoted in western Chinese restaurants (at least the ones where I've been) is unbelievably greasy and sweet. But guess what, the food being eaten in China is not sweet, sugar and soy sauce being used only sparingly in only some meat-based dishes, but that's not the norm.
Also singling out one nutrient or another is reductionist science and represents everything that's wrong with western nutrition and health-care. Remember cholesterol? That was a fucking fiasco for which the medical community never apologized for. We need more Omega-3? Sure, put some in the supermarket sliced bread. Does our food have so much high-fructose corn syrup or other corn derived substances in it, that we can effectively be called the corn people? Oh, point to the Chinese for also eating sweat stuff. Do the French eat saturated fats and wash it with wine? Call it a paradox.