I don't have so many myself but somebody with a lot of (quality) posts I think has more concern for their reputation in the forums than somebody without a history here. Does eBay feedback not work the same way?
+1
A possible reason is bec -
Many people here have met before at a "ddf DO" and now know each other personally.
Most of the attendees at ddf DO's are members who've been around for awhile/have higher post counts. (Anyone is invited, but usually the ones that attend are the ones that are around for awhile)