I think this is a calculated decision on the part of the airline, as gate assignments do change from time to time. They want us to watch the monitors to get updated information.

This is a guess, however. Anyone from the airline, please correct me if I'm wrong.

If you check-in at the counter the agent will usually indicate the gate on the sleeve that holds the boarding card. I use a lanyard, so I tell them they can skip the sleeve, which sometimes results in a strange look.