This is far from the truth. There is a standard
written language, yes,
but it is based on Mandarin. Colloquial writings in regional varieties
use different grammar, different vocabulary, and even different
characters. (The popular book "he zanhwa" had to be translated to
Mandarin before it could be read by non-Wu speakers)
You are discussing an extreme example. Look at all the broadsheets in
Hong Kong(where most people only know how to speak Cantonese, not
Mandarin), and their newspapers can still be understood by mainland
Chinese. Of course some tabloids would use distinctive "Cantonese
characters", but there are really not the standard.
And really what is the use of setting up a Wikipedia if only *one*
user is interested?
[[User:Formulax]]