Lots of games do this. It can prevent people from simply trying to advertise or do what others would consider inappropriate.
It's fairly easy to actually download a game and do malicious things.
For example, you can't spar until you've played a certain amount of hours. You can't enter towers or hit the flag without being in a guild. And now you probably can't put things in your status or say much without being identified or have a certain amount of hours. This can prevent predators from getting easy advertising or manipulating efforts, and simply stops trolls of any sort.
It may not seem like a big deal, but it makes it easier to do this than to answer hundreds of reports from kids who saw naughty words from a troll account by banning these malicious people. Sometimes it's better to limit intent rather than enforce against malicious intent.