…yes, true. On a typical single locus (on some loci, such as SLC24A5, most of the variation is between groups). But that doesn’t mean that you can’t use genetics to differentiate population clusters. Here are 938 individuals (the points) from 51 world populations (the color of the points) displayed on a figure with the two largest principle components of the variation.
From Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation. Also see Lewontin’s Fallacy.