I think 'homogeneity' as a term is not entirely clear. You can say 'ethnically' homogeneous or 'civic' homogeneity. I believe the second one is what you are referring to. On the other hand, the first case might not necessarily apply. 'Ethnically-derived' nations, for the lack of a better term, do and still do have the types of problems that are present in any groupthink society, but we well know that there were trailblazers and philosophers in each of them who did shake up things in those nations, for good or bad, to make it hard to be rigid on the idea that those nations will [fatalistically] end up collapsing as a society because they are too fearful to break consensus.