@shewolfnm,
I think any site is safer without PM's as people can't get at more vulnerable forum members in private.
There are psychological dangers on the internet, for adults as well as children.
Not all forum members have the same level of emotional toughness. Others give away information that other posters/readers take advantage of. We've seen a few examples of that at Abuzz and A2K over the years. I've seen it at other sites as well.
Without PM's, people get to be idiots in public - and can be called on it by the community.
Some people consider what they post publicly more carefully than they do what they put in PM's.
People generally won't post their names/locations/emails on public forums - tend to be looser about that sort of thing in PM's.