I couldn't see the article either.
But, yes. Harry Potter fansites are phenomenal. MuggleNet, TLC, Veritaserum, Snitchseeker, HPANA, Potterish, and countless others have completely revamped the way information is provided and discussions are made. And that too about something fictional.
I've been a lurker here at Veritaserum for ages. And I have also seen how the forums have grown, and countless theories, some scarily accurate and some amusingly random.
Till the DH movies, it is still going to stay strong. And I don't really see why it should stop there either. After all, there are LotR fans out there.
Fansites have brought together people and fans from different parts of the world and some of us have become really close friends. Mine own example, I have made some really close friends from various parts of the world, France, US, Australia and in India too.
I have been running an Evanna Lynch Fansite -
Luna Fans - for two years now. And from it too, I have become friends with people I didn't even know existed, garnered knowledge and learnt so much about teamwork. It's really amazing how something that was run as an experiment can change your whole perspective towards a thing. And make your compassion grow along.