I was referring to someone saying "works for suburbs I'm guessing - I don't see how it helps out in metro areas?". A "metro area" is by definition the overarch

I was referring to someone saying "works for suburbs I'm guessing - I don't see how it helps out in metro areas?". A "metro area" is by definition the overarching container (often including multiple cities and the suburbs of those cities, such as the Bay Area metro area), most definitely containing said suburbs. So if something "works for the suburbs", it works for the metro.