Ok, if you don't mind, I'll use Cincinnati as an example anyway because it's pretty illustrative on on what the issue is.
Think of the general population of urban Cincinnati and what you think their voting preferences might be. The city would probably be represented by liberal politicians at the local level. Now look at the Ohio districts which determines where congressional representatives come from.
Notice how Cincinnati is carved up between districts 1, 2, and 8. Strange, right? Wouldn't it make sense to have the city be it's own district smaller, contiguous district instead of splitting it into 3 misshapen ones?