These occurrences have been increasing lately, and it's usually for the performance issues Dash descibed above..one thing we can do is get small items off the A La Carts (like backpacks) and take them out of the pit and into the main cabin..I've been able to get people on that way.
The bigger problem is the gate agents not wanting to make the effort to notify captains, and being parked miles away from the terminal so captains aren't making the trek to get inside and see who's standing around.
It's also worth noting that Alaska management has deemed Horizon captains as PIC only when the plane is in the air. They continually stress through notices and disciplinary action that we have no say as to what goes on when we are on the ground (e.g. when it's ok to board, when the APU can be ran, how much fuel you can take etc.) It's truly embarrassing to work here sometimes.