My site is a U.S political site so I'm pretty sure no one from China or Russia would have any input. A heavy amount of my spam comes from these two places. Would it be possible to block entire countries?
True. But if he is asking here I thought that he wanted a plugin for MyBB instead of doing things inside his hosting.
Also, he only asked to block registration, not access to his site. This plugin is overall user-friendly for those who are not experts in this type of things.