>Didn't these sorts of cross-country, epidemiological studies
>provide much of the early emphasis for low fat, high carbohydrate
>diets?  I don't know the history.

Yes they did. A famous example is The Seven Countries Study back in the
1950s showing a positive relationship with saturated fat intake and
coronary heart disease death rates in westernized populations including
Cretans. That relation was not more convincing than Grant's between fat and
AD. And the outliers loooked more like outliers.

Keys A. Seven Countries. A Multivariate Analysis of Death and Coronary
Heart Disease.Cambridge, Mass.: Harvard University Press, 1980.