Dilution of content is indeed an issue for Arduino community (although less so than many other tech fields).
That said, I think this Stackexchange proposal for an Arduino site will definitely be useful in certain aspects -- Stackexchange emphasizes content creation and curation in a way that is future-reader-friendly. So this will result in more signal-to-noise ratio, community-voted answers, and less redundancy, but also quicker access for any information an Arduino user might be interested in.