Or to not be accountable for their opinions..
If you want a wide range of discussion then it is helpful for people to be able to throw out ideas. And why should an individual be accountable for their opinions? Chatham house rules normally apply when discussions are happening not when decisions are formed and made.
Do you think people on this forum should be accountable for their opinions in which case should pseudonyms be removed. (and it was a big deal for me putting my name in a forum).