How did a shared writing system encourage people to call Chinese speech forms dialects?

The classification of various Chinese speech forms as "dialects" is largely rooted in the existence of a shared literary language, known as wenyan, which is written in a unified system of Chinese characters.1

Because this writing system is logographic—meaning each character represents a unit of meaning (a morpheme) rather than a specific sound—it functions independently of the diverse oral pronunciations used across different regions. Speakers of mutually unintelligible varieties, such as Mandarin, Wu, or Cantonese, can read the same texts by applying the rules of their own local pronunciation to the characters.231

This common literary tradition, which historically served as the standard for writing, has fostered a cultural and political perception of these distinct languages as regional dialects of a single Chinese language. In contrast, scholars typically classify these varieties as separate languages because they are mutually unintelligible in speech, differing in pronunciation and vocabulary to a degree comparable to the Romance languages.1