Communication is not a yes-or-no but rather a more-or-less affair.

It is, indeed, virtual dogma that the function of language is communication.

The big change, the really radical change in communication, was in the late 19th century. The shift from sailing ships to telegraph is astronomical. Everything since then has been small increments, including the internet.

A language is not just words. It's a culture, a tradition, a unification of a community, a whole history that creates what a community is. It's all embodied in a language.