There is an epidemiological experiment that has been going on for over a million years. It resulted in a population of 8 billion homo sapiens. That is not actually good for the Earth, but if you want to know what to eat, to maximize your health as an individual, look that way.
Not with modern food science. A lot of people consider cornsyrupy sugar water to be satisfying because companies have collectively spent billions and decades in R&D and marketing to make it taste and look as satisfying as possible.
It works because our sense are not infallible, they can be tricked and purposefully mislead. Just like taste expectations are often built from childhood on.
Mainly it's the language that is used by people who adhere to diets such as this. There is more reference to the health properties of various ingredients than there is the art of cooking, and this feels alien to people like myself. Of course, there are paleo foodies (just as there are vegans), but they are in the minority.
I'm not saying the way you see things is wrong (if anything, the fact that you're almost certainly healthier than me is strong evidence to the contrary), but for evangelists of alternative diets there is a cultural barrier to overcome that vegans especially seem to just not be aware of.
Yet, for God knows what reason, whenever some vegan is trying to convince me of the merits of their diet, they hand me some godawful dry sausage made of hydrolysed soy protein and say "see, it's just like a real sausage. Did you know she's Paul McCartney's daughter?". Or some fermented cashew nuts smeared on a piece of bread that they think is anything remotely like cheese. I have never understood this and have since reached the conclusion that most vegans are closer to paleo, gluten-free (not coeliac) and other alternative diet folk in that they just don't "get" people who derive a massive amount of pleasure from food.