There is nothing stopping you from saying anything.
What's stopping you from proxying or using a public service? Most public libraries don't get your name etc, and you can just walk in. Net cafe's are cheap. Want to cover your ID? Fill in the Email spot with anything. You are all more Anonymous than you think you are. I've been accidently deleting posts made by one of my moderators, because he was posting without his nick/trip.
The only information I get is the data you requested/posted, the IP originating, and the user-agent. I can't get anything else.
It's not illegal if you are saying that you are doing something, only illegal if you go out and actually do it. Grouphug is a fine example of this. Random users confess to acts of theft, violence, paedophilia, rape etc. I don't think they are in hot water about "witholding evidence".
You want to talk about the topics on the net that aren't the kind of thing that you wouldn't blab your name with? That's what here can be used for. Want to talk about filesharing? Go right ahead. Want to talk about hacking? Well that too. I never wanted this place to be at ground level with the net culture. I wanted it to be underground.
If you are smart, you'll censor yourself to prevent getting caught. Don't post URL's that will identify you, or other names or details.