I guess I don't see what Anonymous can really do either, unless they can electronically steal all the money the cartel has... then they're just another brand of thief... oh wait... they already are thieves and vandals.
I guess if bad people want to screw each other over and some good comes out of it, then cool, but really who cares? Its not as if another cartel wouldn't rise in any vacuum created by the Zetas being taken down. Its not going to bring back the people they've killed. Its not going to stop illegal drugs from coming into our countries and wreaking their havoc on our society.