This is pretty standard. Google Groups bans me whenever I open too many tabs at once. It's annoying, but these big corps don't have any inclination to support user behavior other than standard, especially when closing down a product. I think the blocking bit is sensationalizing it a bit more than is the reality. The site policies and design intentionally prevent joining a group just to download everything, it's not an intentional blocking of a group or action beyond the default behavior of enforcing the TOS.