More generally: why have more than one representative at all? Because every person has a slightly different perspective based on where they're from. The wider the variety of opinions (at least to the degree they reflect the diversity of opinions -- urban/agricultural/wilderness; male, female; different levels of education and background; etc) -- the more useful the result.
Assuming you're naive, here's an example from today's paper: https://www.nytimes.com/2018/12/31/opinion/childbirth-injury...
More generally: why have more than one representative at all? Because every person has a slightly different perspective based on where they're from. The wider the variety of opinions (at least to the degree they reflect the diversity of opinions -- urban/agricultural/wilderness; male, female; different levels of education and background; etc) -- the more useful the result.