I had to deal with someone in my life who said something to effect of "if you're condemning modern colonization, why don't also condemn the Viking conquest/colonization of England?".

What I said to him was that while I don't know the specifics of that era, let me ask you... can you identify the continuing legacies of that colonization? Ongoing material problems? Can you point to how that still harms English people or helps Norwegians to this day? Pretty obviously, the answer is no. The viking conquest of the English coast doesn't really impact us today in a meaningful way. However, there are a whole host of very real issues that impact colonized people to this very day. So many problems that modern colonialism + capitalism have caused, and basically none have been made right.

The point about bringing up modern colonialism isn't to wag our fingers at the evil mayos (though that is fun). It's to highlight how the people there still are haunted by the effects. Kinda similar to how while as Marxists we may find the bourgeoisie to be immoral, ultimately our critique of capitalism lies in the system itself and not on the morals of individual actors.