The important thing is whether it serves well as a predictor.

If we were that interested we could do a scientific analysis, counting coffee shops and chicken places in different urban areas, averaging incomes, checking trends etc.

But since it's not that important to most of us, we can just use it as a kind of gauge of where things are going, and judge for ourselves if it has merit or not. Might help someone make a few bucks by buying property in the right area (although the most succesful of tose people already use this and a ton of other metrics, plus insider knowledge of future municipal plans etc).