not necessarily, there is often a clear split between social classes of groups of people (i.e. consider the association of "cockney" with working class, or the discussion around "ebonics" for african-american-english)
And there are cases where specific communities evolve their own sub-languages (e.g. cants and argots).
There is surely less separation now then there once was, but it never was only geography, it's just that geography is the strongest separator.