[ksk]

>Sure, plus the countless others who lead a healthy, low-carb lifestyle.

They are not countless though, people who have at some point in time, experimented with keto or low-carb diets are in the extreme minority (I did as well). And an even smaller subset would be the people who have completely switched over to a keto diet on a long term basis.

>Not "because", but "in spite of the fact".

That is merely an opinion. We can't do the experiment of not having a certain adaptation. Having the option of surviving on a variety of diets, including heavy carb (vegetables/fruits) diets, is definitely an evolutionary strength.

> hut rather that they aren't necessarily for leading a healthy lifestyle, as OP's remark suggested.

But practically speaking, the vast majority of healthy people consume carbs. There is no evidence to suggest that a keto diet is capable of providing the same result - in a large portion of the population (comprising of various genetic makeups and other factors), over a large period of time.