The seats are assigned. People have been standing in line for 15 minutes now. Why on earth would anyone want to stand there, when they could just sit and wait until the line clears?
I understand wanting to get off a plane ASAP, but boarding? You just end up sitting on the plane, waiting for everyone else to get on.
How do they bump you to an earlier flight? You turn up for the flight you have a ticket for and they tell you your plane left 2 hours ago?