It's most often associated with Argentina because there's where it appeared to have "succeeded."
But elites in the other countries in the region made similar efforts as well - by way of everything from wars, to domestic raids and genocides, abstaining from pandemic prevention (when it appeared to most often affect Black and Indigenous people), etc.
The real reason Argentines are mostly white (around 2/3 I'd say) is because a country of 2 million people in 1875, was flooded with 6 million mostly European immigrants by 1950.
Imagine - if you will - that one billion people from China emigrated en masse to the U.S. over the next 75 years....
Suffice it to say, the U.S. population would look very, very different by 2100 - besides having a very different culture and even accent.
That's why to this day most Argentines (except northerners), have that Italian accent - even if they're not of Italian descent.
But yes: Argentina certainly has its share of right-wing racists - nearly all of whom were Macri voters in 2015 and '19, and Milei voters in '23.
And that's why Trump has such affinity for the smelly little lunatic.....although rumor has it in Buenos Aires, that Scott Bessent has his own motives here:
Argentine investments (though a cutout, of course), and, reportedly, a mistress.
A regular Mark Sanford, that guy.