DU has done a lot right to be around as long as it has and be as large as it is. Although unfortunately with size it's more likely to run into bad apple agents. It sounds like most happy people have been with DU a long time and have been with agents around a long time and it's a nice marriage. Most of the long time agents likely have other long- time guests, so that leaves most new bookings to be assigned to newer agents with fewer clients. And maybe the newer, less experienced agents are not yet up to snuff or haven't been fileted out yet. Lots of guessing here so I could be way off.
ETA: filtered* But leaving as fileted because it made me laugh.