I really can't imagine how a group can operate that many accounts. I think these are the work of freelancing training centres, where they teach students how to earn from Bitcointalk, and then they join the bounty campaigns and signature campaigns. Our country has many training centres where they teach how to earn from the internet and then let the students start working on various captcha typing and P.T.C. type websites. I wouldn't be surprised if the accounts belong to such an organization, where they operate these accounts as a large group. I think one person or two people can't operate that many accounts. I am not saying these groups belong to a specific country. But it's my personal opinion.