I'm a frequent traveller, but I just got into a peculiar situation, that I don't think I've encountered before.
For some reason, the self-check in machine at the gate did not give me a ticket with my assigned seat number. The stewardess asked me to wait untill everybody had boarded, and then pick an empty seat. No problem – and probably not relevant to the story. I picked a seat in the aisle at row 6 (so fairly in the front of the plane).
A lot of people were travelling home for holidays, so the plane was almost full, and most people had a lot of carry-on luggage. A passenger had blocked the aisle just behind me while taking out their luggage from the overhead compartment, thus leaving me an opportunity to exit my seat. As I walked up the aisle alone, the stewardess then blocked the door, and asked me to please wait a bit to let other people "catch up".
After about twenty seconds, enough people had queued up behind me, and I was finally let go.
The question is, why did she not let me disembark alone? I was not rushing out, but walking in an orderly fashion. The five rows ahead of me had already disembarked.
I thought maybe it was to keep passengers together, so groups with children was not separated. However, I was clearly a single-travelling passenger, everybody seemed calm, and I was walking up the aisle alone (story of my life, eh?).
The plane was already an hour late, and was (to my knowledge) the last to land that night. The airport did not seem busy at all, and airport personell were simply waiting for us to disembark, so they could go home.