By this standard, the African bush and the villages of India should be full of thousands of "races" because of the high genetic diversity and relative reproduct

By this standard, the African bush and the villages of India should be full of thousands of "races" because of the high genetic diversity and relative reproductive isolation of many populations therein, which far exceeds that which delineates our conventional racial classification. But in the real world, race always refers to the same old Negroid/Caucasoid/Mongoloid classification that a few Westerners came up with in the 1700s. Why is that? Does it feel plausible that Science fixated on the Biologically Correct racial classification of humans over a century before Mendelian genetics and the germ theory of disease became widely accepted? Or is it perhaps more plausible that racial classification came into vogue for other, more unfortunate reasons, which are now well-known and documented, and then persisted by mere inertia and conventionalism/conformism?