I’m sorry, but the OP is pretty much riddled with unsubstantiated lay person’s assumptions about the present-day life of dogs, canine nutrition, commercial dogfood and a few other things. Drawing conclusions in this way from facile assumptions and superficial analogies is always risky business!
Try to make it real, compared to what? “The vast majority of these animals live long healthy lives” – compared to what? Can you back up that sweeping generalisation with some facts? I’ve been in the dog game for most of my life and a lot of evidence indicates that the vast majority of dogs are living shorter lives than they did 50 or 60 years ago, and that serious diseases of all sorts are proliferating in the canine population. Some of this is being blamed on questionable breeding practices, and rightly so, but it seems likely that diet (as in the case of humans in North America) must bear its share of the blame too.
Commercial dogfood is a more lucrative proposition than one might think – if not, why would manufacturers spent so much money on high-priced national advertising? You don’t mount multimillion-dollar ad campaigns without the virtual certainty that the investment will be repaid by sales in many multiples. Commercial dogfood is concocted from extremely cheap ingredients, many of them waste byproducts of human food processing industries – beet pulp, for example – of little to no nutritional value, possibly harmful through its saponin content, it’s a valued ingredient for most dogfood manufacturers because it keeps stools formed when they might otherwise be diarrhoea, and it gives a false bulking effect through its ability to absorb up to seven times its weight in water. Similarly, soya-based rations are a feature of cheaper brands, despite evidence that soya protein is of dubious value to carnivores – and the dog IS a carnivore.
“Without the vast body of research that exists into optimal human nutrition” – well, there is some research, unfortunately nearly all of it is funded if not actually carried out by major stakeholder corporations like Purina. Actually it’s a bit difficult to determine what the nutritional requirements of the domestic dog might be, although it’s quite obvious what Purina thinks about the subject! In short, a lot of well-funded research has a predetermined outcome, i.e., the justification of soya protein, beet pulp and similar issues.
I don’t think we should take the OP’s analogy seriously. Several of the stated major premises are open to question, so subsequent reasoning from them is void.
FWIW, though, I know one guy on the CRON (Calorie Restriction with Optimum Nutrition) lists who subsists on Purina Lab Chow for Primates, plus chopped raw cabbage. Speaking of “one meal for life.” In fact, the “one meal for life” approach has its advocates among CRONies, because it’s possible to construct such a meal from the ground up for “optimum nutrition” – to whatever degree the current state of nutritional science permits us to comprehend the full meaning of that little phrase.
Personally, I think “one meal for life” is something of a quixotic enterprise. It’s a grand, idealistic goal but I would question whether we are anything like close enough to knowing the full meaning of “optimum nutrition” as yet, to the degree that would make such a goal attainable. I’d call it “The Impossible Dream”