rumination on why wiki works and not

IRRODL: Educational Wikis: features and selection criteria
makes this observation

Godwin-Jones (2003) suggests that wikis may be ideal for building communities of practice by creating a collective repository of expertise in a subject area, which is refined over time by the contributions and problem-solving of interested individuals. It is this function that distinguishes communities of practice from other online communities, such as chat groups or bulletin boards.

a reference to this

Blogs can be highly personal, wikis are intensely collaborative. They feature a loosely structured set of pages, linked in multiple ways to each other and to Internet resources and an open-editing system in which anyone can edit any page. […] Such a system only works with users serious about collaborating and willing to follow the group conventions and practices.

Teaching with wikis draws on principles that comp/rhet theory have been teaching for years: the use of collaborative, project-based, guide on the side learning, letting students assert genuine autonomy over the process and product in a genuine writing space. To work, wikis require committment. The payback is expertise in a powerful writing space that can change what and how we work, what we can do with writing.

I suspect that wikis will be valuable in courses that frame themselves in convenience and utility because wiki requires commitment that goes beyond the course itself.