A bulletin board, without any moderation can devolve into complete anarchy. Our board had done that. Once a certain mass has been reached, bulletin board discussions degrade. There are people who have a need to assert themselves via posts that attract attention. These types of people are not the lion share of the public, but given enough numbers on a bulletin board they can have a negative impact on all the discussions. The larger the board gets, the faster it devolves.
In the real world, there are natural inhibitors to bad behavior. A normal person would not walk up to a guy three times his size and make derogatory remarks about him or his date, lest he get punched in the face. Only an idiot, not willing to accept responsibility for his actions, would do so.
Bulletin boards have no natural barriers to prevent bad behavior. Thus it is quite easy for them to devolve into anarchy and chaos. Do some people get upset when they get moderated? Yes. Those who cannot accept responsibility for their own actions always get upset.
Is moderation an exact science? No. Any time anyone has to make a judgement call it will be subjected to the masses for them to judge and re-judge. Everyone has their own perspective, on any given attempt to moderate, and they will gladly tell you how wrong you are when you do moderate a discussion.
Truth of the matter is; If there were natural barriers to bad behavior, a bulletin board would never need to be moderated. Discussions would take place, not 'look-at-the-next-shocking-thing-I-can-say-to-get-attention-and-how-I-can-disrupt-a-discussion' posts.
Our bulletin board, whether we like it or not, is a representative of our business. It is not in our best interests to allow it to devolve into chaos. The unfortunate truth is, controversial topics are a catalyst for bad behavior, on large bulletin boards. We tried everything to keep from going down the path of denying topics from being discussed, and nothing worked.
The only way our board got back to an acceptable level of civility was by restricting the topics which can be discussed. We realize there are people who do not care about the civility of a bulletin board, but we have to as it is part of our business.