You weren’t paying attention in the 1980s.
The whole reason for launching multiculturalism was to slow down racial integration which had begun to proceed rapidly (particularly in the southwest) and threatened liberal race posturing.
Why do you think the left got so furious and doubled down on George Zimmerman when his ethnic make up wss shown? They can not afford for Americans to all just be one people.
E Pluribus Unem.
You just had to be a jerk about it.
Racial segregation seemed to get worse in the northeast and rustbelt in the 1970s-1980s. “Mulitculturalism” is part of the proletarization of race that goes hack to the CPUSA’s idea in the 1930s to create a black Soviet in the southern United States.