Nutritionally exact is different for every person, though. Their measurements ultimately mean nothing. You could also, of course, say that about anything ever sold. The product is marketing, not the value of the product. You don't really need to measure things out with a scale, you just throw some shit in a blender, then drink. Take a vitamin every day. You'll probably also end up with something that tastes better, to boot.
Nutritionally exact is a variable target, yet at the same time, the values the FDA and other health organizations have come up with for all micros and macros are determined based on average need for all body types, body sizes, and fitness levels. At the levels they have determined, you will be nutritionally safe by consuming that level, regardless of your personal disposition. Now, if you are heavily into fitness and need more food, you are either consuming additional supplements of some kind, or additional food, and quite likely, adding whatever extra micronutrient you may actually need. The targets are well enough established that it is not a worry to only take that amount.
Again, just randomly throwing things into a blender without minding the levels of individual items, is asking for an unhealthy imbalance. We see what happens when people just eat whatever they want to eat in a day, multivitamin consumed or not, and I'm not referring to fat or thin. The level of heart disease in the US is disgusting, and with careful eating, it is quite easy to mitigate a majority of that risk. Again, Westerners consume so much Omega 6, a known promoter of inflammatory products, because they just do whatever they want to... and hell, it definitely seems that even many health nuts don't understand the importance of balancing specific fatty acid intake.
It's too easy to do it wrong. Do you need to use a scale for precision? Not necessarily, especially if you aren't actually adding pure mineral and vitamin supplements from bulk. But you sure as hell need to understand the full composition of what is going in, if you care to live off of that more often than not. Most people just eat to reach satiety and figure a mostly well-rounded diet will give them everything they need. It's a major gamble, and while many live a long life without ever thinking about micros and macros, more often than not, that's a testament to genetics and perhaps luckily consuming the right antioxidants or other compounds. The ability to shape your immune system and stave off systemic disease or even cancer, that can all be done with food. You can gamble, or you can strive to achieve moderate precision based upon current science.
Science may fluctuate on the ideal proportion of macros, but ultimately, as long as the key micros are all consumed in the right quantities (which, oddly, seems to be easier to understand at a cellular precision level), the beneficial properties of those may prevent negative effects of too many carbohydrates or too many fatty acids.
To sum it up, I'm not saying you CAN'T do what you proclaim to be possible, I'm merely arguing that it is not in one's best interest to try.
I cannot say I have it right, and achieving to only reach pure precision of everything you need for decades on end in order to be healthy in your elderly years is not a readily enjoyable task. Frankly, I'm one who definitely prefers to enjoy food at every level, and have skipped out on some healthy components in my diet for a long time. My actual vitals and bloodwork determined that I am amazingly healthy as of two or so years ago, more so than most in their 20s according to my doctor. But that may hide deeper health anomalies, those that arise from free radical damage or not enough of key fatty acids. Perhaps the bloodwork checks out now but the damage hasn't reached a statistically significant level. That's very much possible and, hell, quite likely. Potential damage such as that is also easily reversed; extensive damage may be difficult to bounce back from, but the body is incredibly efficient at self repair, given the correct nutrients at the right times. Neural health defects from too little DHA can be overcome, to a certain point at least, and I believe it may not work as well in fully mature adults as compared to adolescents.