The Japanese founder of 2ch said that anonymity was to allow people the freedom to say what they really meant. (Wikipedia.)
> A: Because delivering news without taking any risk is very important to us. There is a lot of information disclosure or secret news gathered on Channel 2. Few people would post that kind of information by taking a risk. Moreover, people can only truly discuss something when they don't know each other.
If there is a user ID attached to a user, a discussion tends to become a criticizing game. On the other hand, under the anonymous system, even though your opinion/information is criticized, you don't know with whom to be upset. Also with a user ID, those who participate in the site for a long time tend to have authority, and it becomes difficult for a user to disagree with them. Under a perfectly anonymous system, you can say, "it's boring," if it is actually boring. All information is treated equally; only an accurate argument will work.