See, here’s the thing: the overhead walkway that connects the Convention Center to the Hilton is… oddly designed. The Hilton side is higher up than the BCC side, but instead of doing the whole thing like a ramp, they put stairs at the BCC end. And also a handicap person elevator, which takes up half the hall space right next to those stairs. End result: large crowds bottleneck in that walkway, and Otakon has LOTS of large crowds.

(Historical Notes: I’ve since heard that the people who designed/build the Hilton botched their side of the walkway, which is why it has that weird turn in the middle instead of being a straight line.  I’m not sure if that’s also why the entrances aren’t at the same level, but it’d explain a lot.)