It doesn't need to be as purpose-specific as the title suggests. Blogs are a medium of communication; there are many possible media.

Consider this interaction. A: this rose is green. B: roses are not green. C: (so the rose is not green!). C: actually, it's not a rose, it's a leaf.

This can occur in a blog, in a chatroom, and more importantly, it occurs in everyday life. Proofreading, fact-checking and such is a streamlined application of this self-correction process (e.g., of the ABC system above), applied to written material.

While we are a far way off from AI that can do this on the fly, the processes certainly is extendible, and should be extended. It's how ideas evolve.