Installing a plugin and pressing "Sync" may indeed be improvement over manually merging Word docs, although they do gloss over the hairy yet important bit of managing permissions: who exactly gets access to each doc?

But having gotten used to Google Docs, it's considerably more convenient -- hell, nearly magical -- to be able to just work and have your changes sync in real-time. For example, meeting minutes pretty much write themselves when everybody has the ability to edit the doc simultaneously and summarize what they've just said.