How does colorism help destroy the town in Toni Morrison's Paradise?

In Paradise, Morrison explores the ways in which black people have internalized systematic preferences for lighter skin, and residents of Ruby engage in prejudices based on skin color even without crossing racial lines. Before Haven/Ruby is established as a town, its founders are barred from other communities because dark complected "negroes" are unwanted there. The people of Haven, noticing pervasive social prejudices against former slaves, poorer black people and darker complected black people, see "a new separation": where once white prejudice against black people was the social norm, now light-skinned black people were engaging in prejudice against dark-skinned people.

In what appears to be a subversion of this norm, Ruby becomes a place where darker skin is celebrated and lighter skin is perceived as undesirable. Darker skinned people in Ruby are considered more eligible for marriage; people are described as marrying darker complected people to compensate for their own paler complexions, thereby raising their social station in Ruby. Morrison attributes the colorism in Ruby to a multi-generational legacy of internalized racial hatred, and conveys the idea that Ruby, though seemingly subverting colorism and internalized racism, was in fact mimicking the white race's subjugation of black people.