you confuse "traditional" with "vernacular." They're related, and can overlap, but they're fundamentally distinct.

The vernacular operates in a traditional manner. It changes, evolves according to individual & cultural usage. Each culture has vernacular idioms that are constantly evolving according to the letter of the 1954 Definition. Even inside of the idiom of (say) Hip-Hop there are a myriad of vernacular traditions evolving quite distinctly, and happily.