The truth is, you have to stay around for a while to get to know the people personally. Looking at user levels is worthless for all but one questions: whether you’re dealing with a troll.
While I'm not yet fully convinced about the truth of your claim, especially because I have been on forums where the rank was publicly shown1 and it didn't seem to me to have such a disruptive effect, I completely agree with your observation that "you have to stay around for a while to get to know the people personally". I learned to do so in newsgroups where it is even more important, and some orders of magnitude more important, to do so.
1But not that many so I admit that my judgement may be biased.