Maybe it permits them. But isn't gerrymandering the result of already radical and uncompromising parties that hold the levers of power?
So the problem is that US politics is so obviously racially divided and folks engineer districts to take advantage of it.
If white people and black people and Jewish people etc didn't live and vote in racial blocks, no one would bother to draw these weird congressional maps.
I'm thinking gerrymandering is a symptom, not the disease.