Most people have visited a message board at one time or another in their life. Most of those that have contributed have posted useful input to discussions which are valued by many of the subscribers to the board. It's the small minority, however, which has created the need for moderators. These are the people who read all of the articles and comments posted to a board and ensure that they are suitable for the audience.
Moderators are very necessary.
Quite often they degenerate into meaningless collections of junk visited by no one except automated spamming programs. I always find it sad when I visit a board in this condition. I mean someone put some effort into creating a community on the web, then for whatever reason neglected or abandoned it. The truly sad boards are those that were obviously active, useful areas full of vibrant communications which have degenerated into uselessness. I get every time I visit the long abandoned Marineland in Southern California.