- what kind of languages can have wikis?
any that has a standarized writing system and enough writers and readers to form a viable community and audience. whether a particular language qualifies depends on discussion.
While the basic idea is about right, I think we need to be more precise. If we adopt your criterion, we're going to get disputes over the definitions of "writer", "reader" and "viable". Do writers and readers need to be native speakers, fluent or just have a basic understanding of the language, for example?