Among the couple of hundred countries on this planet, there are way more languages and dialects. Communication over language domains is hard. We need translators or interpretors to cross those boundaries. Even though tech is trying to chip away at this hard problem by automating that, we still have a long way to go. And language is not static, it changes constantly in space and time. As soon as time passes or communities become isolated from others, people change their language for the purpose of their own communication.