They didn’t change the rules. They weren’t jailed for distributing illegal content but for aiding to distribute it. There were no newly-invented laws or anything.

To take up your example: There are no rules on Forumwarz that prohibit to DDoS the servers. However, I am quite certain that I’d get permabanned if I actually did this. This is just to explain why you can’t argue like this, but as explained above, it doesn’t even apply to this case.

What rather bothers me is the general attitude towards this lawsuit. Those people caused damage of several millions of dollars and shouldn’t be punished for that because the prosecuters are idiots?