Its not really a question of banning internet anonymity as much as whether sites like this one want to insist on names in order to make the site less trouble-free for moderators.
The issue of free speech doesn't arise in this context. There wouldn't really be any global agreement on legislating against anonymity. In any event, they know your IP address so youre not really anonymous.
Every government has its secret service branch ... A messy job? Well that's when they usually call on me ... Oh yes, my name is Drake, John Drake.