That makes copyleft licences useless. Wikipedia as a whole has shown great (some would say excessive) dilligence in avoiding copyvios. It also maintains copious data to trace the origins of anything in an article. This makes the likelihood of such a suit remote. It means that there is no realistic protection whatsoever for copyleft material. It means that any downstream user, particularly a commercial one, can take anything from Wikipedia, and republish it under his own copyright without any fear that it will be seriously challenged. I accept the GFDL position to allow the material to be re-used by commercial interests, but any commercial interest that uses it needs to acknowledge its viral nature. Who defends that? Who defends it 20 years from now?
Baidupedia is a public website: that is, if they improve our GFDL-licensed work, then anyone can use those derived works under the GFDL; whether or not they acknowledge it or advertise it doesn't change that fact. Therefore, I don't see copyleft being useless in this instance.
-- Matt [[User:Matt Crypto]]