[comex]

It's not about giving anyone assistance or an advantage, it's about giving people representation. With single-member districts, if a group makes up, say, 20% of the population in each district, they don't get 20% of the representatives, but 0%. If we had proportional representation, they would get 20% of the representatives, but we don't, and majority-minority districts are basically a bandaid to simulate it in a subset of cases.

To be eligible for a majority-minority district, a minority group must be "politically cohesive" and "sufficiently numerous and compact to form a majority in a single-member district", while the majority group must "votes sufficiently as a bloc to enable it [..] usually to defeat the minority’s preferred candidate". (Thornburg v. Gingles) In other words, there must be a political bloc that (a) is not receiving any representation in the area and (b) would have representation with a majority-minority district. Letting them have that in no way gives them an advantage over the majority, whose preferred candidates will still control all the other districts.

Why not apply this to political blocs that exist based on factors other than race – like plain old conservative versus liberal? Well, I think we should; again, I'd prefer proportional representation. But the current rule is enforcing the Voting Rights Act of 1965, which specifically calls out discrimination based on race – something that was a huge problem in 1965, and is still a problem today. Compared to other types of political blocs, racial ones are disproportionately excluded from the political system. And morally speaking, although being discriminated against due to your political beliefs is bad, being discriminated against due to your race is somewhat worse, because you can choose one but not the other.