There's limits to how much you can dilute a city with rural vote sinks because every district has to be geographically contiguous. Whereas there's very little limit to how much you can dilute rural represenation with densely packed urban vote sinks. -OS
Hence why you can draw a 52-0 map in CA. Democratic votes are so densely clustered around LA and the Bay that you can simply draw a map where every district approaches one of the two major metros and theres more than enough Dem votes to go around. -OS