Thanks Andrew Boon for looking this way.

A Group that draws it's membership from all classes of personality will often times be large.

Then everyone is free to post contents. Large public and free joining groups has always come with attendant issues of abuse.

To prevent abuse and institute sanity, this contents are pre-moderated before it goes live.

The basic and most common is blanket for all content posts from non-admins. Powering with exemptions for selected profile levels will ultimately puts Facebook behind.