You just have a quirky understanding what a language actually is. Language names are given and defined in language themselves, and it does make a world of a difference if you say you speak Swedish, Danish, or Norwegian, even though they are quite MI among each other, and even somewhat MI with German.

Linguists do refer to different languages in China, which are referred to by the government as dialects. So there is much more to it than politics. In your definition probably the whole Indo-Germanic family from Norwegian to Farsi or Hindi would be one language.