Standard language is a codified form of a language, which represents its official form. It serves the purpose of overcoming dialectal variants, and being universally understandable by its speakers. In order to be fair for everyone, it is supposed to be based on a certain dialect, but not to represent any dialect in particular.
Language naturally consists of its dialects and varieties (we'll leave the discussion of the difference between a language and a dialect for some other time). Most, if not all, linguists would agree that dialects are the richness of a language and that they should be preserved. However – at least in the case of Serbian and many other Balkan languages, but probably even more universally – the sentence they use: „You should care for your dialect…