Homogeneity, insularity, etc. leads to degeneracy. It leads those victimized by such homogenaity being simultaneously ignorant of – and bigoted against – those viewed as “foreign”, or (collectively) “other”.
This is why I’m glad to see the increasing proportion of “Non-Whites” in formerly lily-white regions (such as “Pennsylvania Dutch” country: such “desegregation” FORCES everyone to get out of their (demographic) “comfort-zone”.
“Self”-segregation is still segregation, and will still lead to the twin evils of ignorance and bigotry.
That’s why I’ve concluded that “homogeneous” areas must be utterly destroyed — NOT (necessarily) in the sense of being totally annihilated, but rather, in the sense that their homogeneity must be obliterated.
Ideally, even “self”-segregation should be impossible, by any means other than barricading oneself in ones own dwelling.