Do you think that an Inuit, or a Massai, who have eaten a very meat and fat intensive diet (up to 50% animal fats) and have done so for who knows how many hundreds or thousands of years would do well as a vegetarian?
No, they would not...
In less harsh environments, most ALL native peoples were hunter gatherers before agriculture - and ate primarily local in season foods... the same argument some use against the consumption of dairy, could be used for the consumption of grains as well.
The debate over a one size fits all way of eating is a bunch of crap, perhaps always has been (unless you believe in the Garden of Eden - but we have come very far from that). Yes, some people may benefit from a near vegetarian diet; even Gandhi tried to be 100% vegan on many occasions, some of those *experiments* with his followers as a study in order to provide proof. He couldn't do it, and after several tries, acquiesced, realizing that some raw dairy (think about his ancestry and gene pool here) was beneficial to health and well being... however, vegetarianism, or veganism, will, and has made others sick who are not genetically adapted to a fully vegan diet.
That is why, building one upon the other over the last 30 years or so we have found that, the Blood Type Diet showed benefit, then the metabolic typing diet showed us even greater benefit, and now diets tailored to an individual's specific genetic traits are being found to be so very beneficial for healing, health, and well being... and yes, what they are finding is that many genetic adaptations benefit greatly from animal fats, proteins and nutrition of some kind... as a primary animal food source, some may benefit more from fish and seafoods, some, red meats, others white meat, and still others raw dairy will prove to be their most beneficial genetically coded food.