When I first got here from Envoy, I wondered the same thing. From what I can figure; Regionals don't leave the gate without a closeout, because passengers seated in the appropriate zones is more of a W&B issue on the RJ's than it is on the larger jets. As soon as boarding is complete, we close the door and call for push. Usually the closeout comes during the pushback. But sometimes, it comes much later, if the load room is behind on running numbers (cargo, ect...).