than I've had from BA and NCL in the last 24
BA cancel a flight and NCL get the blame?
Some friends flying from NCL on a Sunday a couple of weeks ago were actually put on the plane before being told they had hours to wait.
Delays are fluid - there may not have been a delay when they got on, alternatively there may have been an ATC or weather delay but there was a possibility of an earlier departure. In that case it is better to have PAX on the plane ready to go than wandering around the building or "popping home cause we've got a couple of hours to kill". Probably not an issue at NCL but can also happen so that the a/c can be moved to free up a stand for an inbound flight.