[breischl]

You seem to be thinking specifically about documentation for one particular project, eg API docs. And in that context I'd agree.

But Wikis are useful for things that are shared, or that are not tied to a particular product, or don't exist in the product yet. eg - "What's the temporary workaround for this bug?" - "How do I get started as a new employee?" - "What information do we need on customer requests?" - "What's the team process for handling escalations?" - "Here's the preliminary design for this new feature"

You still need someone to update those docs, but it's nice if, eg, the manager (or product/project manager) who isn't in Git all day can do it easily instead of asking a dev to do it.