I think they need to make It so you can only have one tag at a time so they can start penalizing guilds as a whole for blocking. If guilds got penalized the guild leads would have to be more involved in controlling their members behavior and it might cut down on the blocking. If a guild leader is caught cheating a 2nd time they will be forced to relinquish ownership of the guild to the co-leader.

There would also be a cool down time before you would be allowed to receive tags or invites from other guilds. To make sure your not hoping guilds to avoid getting your guild in trouble or making another guild get in trouble. You would not be able to leave or join another guild with in a certain period after being warned or penalized.

There could also be some kind of notation on each individual players statuses showing that they have been warned and after a "probationary" period it will be removed. Like a little yellow or red card similar to what players get in soccer. If you get warned for anything you get a yellow box put on your status screen that will stay there for a month. Then if you have the yellow warning on your status and you commit another infraction you get banned and a red card on your status. That stays on until your ban period is over then when you come back its red for the first month then changes back to a yellow card for a short probationary period. If they commit a 3rd infraction while having a red box they are banned for life.

They could even use this penalty system on guilds as well by putting a warning box in the guild news.