Absolutely, if management is entirely invested in it, and it becomes a mandatory part of the process (e.g. updating the wiki is a part of a release or new build), it can be a critical resource. The problem is that the organic nature of wikis lead to people believing that it will just emerge, in the same way that the relatively unstructured wikipedia eventually became a critical resource.

But citing wikipedia is often folly. The man hour to output ratio of wikipedia is absolutely enormous. It is an extraordinarily inefficient process that works because there are millions of people moving, structuring, contributing, making templates, rewording, reorganizing, etc. Eventually greatness emerged.

I agree. The biggest difference that came to mind when I read your comment is that a personal wiki doesn't have the economy of scale that Wikipedia has. With Wikipedia, the effort of hundreds to organize everything can benefit millions. With a personal wiki, the dynamic is different. I 100% agree that there's a real risk of a 'honeymoon period' giving a false sense of ROI, and I've fallen victim to early enthusiasm about various organizations strategies that ended up not lasting more than a month. I've resorted to a to-do list and a chronological work log as mechanisms that require little organizational investment but yield many of the benefits of a more sophisticated system.