Absolutely, just because population A does well on some diet doesn't imply everybody does.
Actually that is for me often a good heuristic to discard most nutrition advice right away. A lot of recommendations I see include lots of diary products. Yet 16% or more of the (European) population are lactose intolerant (even more in other countries). So that advice simply can't be true, and it seems like a good idea to regard the rest of it with suspicion, too. I guess that at least shows it is not completely hopeless for the individual, some common sense might go a long way.
A lot of people are Fructose intolerant, yet the "an apple a day keeps the doctor away" advice won't die.
Then again there is a lot of fear mongering about milk going on. But the ability to digest lactose (as an adult) spread like wildfire at some point in time, seems to have had some evolutionary advantage.
"my body tells me what I need" doesn't reliably work either, because it might crave for sugar, alcohol and nicotine :-/
Nassim Taleb avoids foods that haven't been eaten by his population for thousands of years, for example Mangoes. Might be too extreme, but worth thinking about. Atm there is a new craze in my country about some new healthy grain from South America. I pass - it seems obvious that people can be healthy without that grain (because people have survived in Europe for millennia), so why risk it? So maybe if Bananas were a new fad I would feel the same way, I only eat them because they were already a fad when I was born.