Wikimedia already has a longstanding preference not to
into separate ones for each dialect, as much as possible. Therefore
nobody would support splitting the English Wikipedia into
American-English and British-English and Australian-English Wikipedias,
and similarly a *lot* of effort was put into keeping the Chinese
Wikipedia from splitting into Simplified and Traditional Chinese
Wikipedias, and efforts to split off a Cantonese Wikipedia have also
been consistently opposed.
American, British, and Australian English can hardly be termed
dialects. They're better termed as standard varieties of the same
language, because each of them has several "acceptable" accents, and
the differences are almost entirely limited to terminological
differences. (for example, is someone "in hospital" or "in THE
hospital"? are they "in the OR" or "in theatre"? did they get
poisoning from "rotten eggplant" or "dessicated aubergine"?
Also, perhaps you've been hiding in a cave for the past year -- the
Cantonese Wikipedia's been around for a while now, and the vote on
whether or not it should exist showed a clear and strong majority of
supporters, while the opposers were a vocal few (read: Andrew Lih).
Also, you might check the two other Sinitic "dialect" wikis created since then:
and of course, http://zh-classical.wikipedia.org/
Refije dirije lanmè yo paske nou posede pwòp bato.