Closing the gate ahead of scheduled departure time

I missed an important flight recently, even though I had arriaved at the airport 1.5 hours ahead of the departure time. Things beyond my control happened after arriving at the airport, and I got to the gate exactly 8 minutes before the scheduled departure time.

Not sure if the airplane was still attached to the jetway, but the gate was closed. The agents said that I was supposed to be at the gate 10 minutes before departure time, and no dispute there. But, trying to understand why they would close the gate when they knew that some of us (my guess is that we were all nonrevs) were somewhere between the self checkin kiosk and the gate. The agents seemed nice enough people. This was the only flight all day that had empty seats.

Of couse, we don't want to inconvenience the paying customers. So, made no fuss, just returned home. But, I now have to wait months to reschedule my medical appointments again. For future purposes, I'd like to know the proper protocal in this type of situation. I am also curious if there is some sort of policy to close the gate as soon as all paying customers are on board. Thank you in advance.

Protocol is bite the bullet and try the next flight. Nonrevs check in online who aren't actually there, so the agents really don't know. They usually page at the desk, but if you aren't present...they may have boarded some nonrevs--did you check? I guess it's better to go a day before for important appointments. That's what we do. Did you try OALs on zed?
Most of us have screwed up timing for a flight...

As a gate agent, I can tell you there is an immense pressure to get a flight out on time. To wait for a late nonrev who may not show up is absolutely not a reason to keep things open and risk a delay. We don't know your reason for taking the flight, and frankly don't really care. I'm not sure what your airline background is, but if you haven't worked that side before I assure you that for everything you see happening, there's at least just as much happening that you don't see. Flight attendant paperwork to deliver, cargo information to give to the pilot, last bags to put on... adding another person would likely mean having to restart the process, and what is usually perfectly timed to get done in 10 minutes is a lot harder to do in 6-7 minutes (there's a good chance the flight is also closed out, so boarding wouldn't be an instantaneous process anyway).

Oops, I had no idea that you could check in on line... I can see definitely why gate agents have to disregard "checked in list" for nonrevs, among other things. Definitely appreciated both of you!

I think it depends on the airline, but most do allow it. I know UA does, and I believe that DL and US do as well. After the door is supposed to be closed, even revs may have a hard time getting in. Considering a nonrev shouldn't really be a cause for anything out of the ordinary (especially when it's under their control) I can see why a gate agent may not bend over too much. That said, I do believe in karma and do whatever I can to help my fellow nonrevs out. :)

It's a blessing and a curse. I like checking in online as nonrev--just use your record locator thru travelnet or delta.com--type it in, then the airport and you can print your BP 24 hrs prior. It's a double -edged sword, since you also declare your priority. I realize it doesn't effect you much as a retiree, but I've seen people change from S3 to S2 when they see high seniority. Some people realize they don't HAVE to burn an S2 if they see who's already declared...
There aren't a lot of folk who checkin and not show, but it happens! Particularly connects. Hope you got all your appts changed easily.