The real reason is the left, after souring on Stalin, decided to make the colonial third world their new mascot noble savage proletariat. Starting with men like Fanon, they just decided that the non-white poor of the world were universally justified in anything against the evil oppressive capitalists of the north. They spewed that nonsense for 50 years and they built entire philosophy departments to justify it, though it was a nihilist embrace of barbarism and murder from the start. The chickens having come home to roost, they are in denial over the consequences. Which are their own speedy extermination.
Use the 3rd world as a battering ram against US capitalism instead of US workers.
This includes bringing the 3rd world into the United States via immigration both legal and illegal
Of course some immigrants are conservative but by and large they will vote for socialism, Democrats and government handouts and so will their children
My opinion is immigrants are way ahead of the native born in using and exploiting government programs. They have networks that help them cash in