To be fair, most of the gate agents in ATL are great, but the few bad apples tend to be the most memorable. And every bad experience with a gate agent that I can remember was in ATL. I once arrived there on a badly delayed flight but had about 20 minutes to make my connection. The connecting flight showed on time but not yet boarding, which it should have been if it was going to leave on time. So I tried to ask the gate agent at my arrival gate if she could call my departing gate to find out whether they were boarding just so I knew whether or not I needed to run for it. Without letting me finish my question, she interrupted with, "They won't hold the plane." I tried again to make clear that's not what I was asking, and she again wouldn't let me finish my question. Of course, this is ATL, so the flight was actually delayed but not showing that in the system, so I made it with plenty of time.

In contrast, in a similar situation with a very tight connection in MSP (the app did show that plane as boarding), I asked the arrival gate agent to call the departing gate and let them know I was running for it. When I arrived at the departure gate, the agent thanked me for having the other agent call.