The problem is, JJ2 is a game where it's easy to imitate others. Unless you have sure-fire proof, you might end up banning someone who's innocent. Plus, when someone is banned, they will be unbanned eventually, in the time that they were banned they might have learned a lesson and it wouldn't be fair to keep them banned forever.

Not to mention how hard it is to completely ban someone, the list servers only ban ip addresses. If the address isn't static, then all they have to do is reconnect to bypass it. Even if it is static, there are several ways to get past, since it doesn't actualy govern JJ2 servers, just accessing them with a friendly interface.