you talk about truth and I consider it a rather hard word, we could discuss long enough if there is such thing
. Personal truths may exist but they may ( should ) change as we learn through life.I consider that wikis and blogs (and forums, cause we could consider a blog as a special class of forum) accomplish different tasks, as you expose. Wiki is a tool to create large hypertext collaborative documents where different minds try to create and consensuate a text while understand each others and create new knowledge while they do it ( doing something called social constructionism). Blog is a way of self expression, through comments, permalikns, rss and search engines the blogosphere allows the revision the knowledge created (but within the blogosphere not in the blog itself).
We should not forget about the tools that wikis offer us to review the process ( page history, examination of navigation, vote for pages, evaluations, and discussion pages ) those tell much about what's going on also.
The use of autoresumees tools and so on can be useful, but I believe that for learning is best to read and follow the links and create the knowledge in our mind.
That's my truth, but I've happened to disagree with myself often
Ludo