I don't understand the apparent desire for early boarding. Almost every airport lounge I've been in has been more comfortable than the aircraft. The plane's not going to leave without you. I much prefer sitting in the lounge and wandering on last.
Space for carry-on luggage is limited. If you board last, there is a high possibility that the airline will check-in your carry-on luggage instead. This will cause you a delay since now you need to wait in the baggage claim area after arrival. Had you boarded just 5mins prior, someone else might have to wait 30mins in baggage claim instead of you.
Ever have this happen? It doesn't happen this way.
They have special space for "checked carryon." they ticket it with a special ticket and put it in a SEPARATE part of the plane. When you unload the flight attendants get the "checked carryon" and put it next to the door, then you grab it on your way out.
I sat on the front of a small plane before and there was no space for carryon at all on that seat. There was no seat in front to put it under, and the overheads on that seat had a bunch of flight attendant stuff in them. Being the first on the plane wouldn't have enabled me to avoid the "checked carryon."
This is by no means how it commonly works.
Some planes will "gate check" your carryon, but most of the time that last-minute checked luggage gets checked through to your final destination.
And for the other comment above, the plane certainly WILL leave without you.
This weekend, my partner had her backpacked gate-checked, but it didn't go to the separate part of the plane. It became checked luggage, which then failed to come off the plane and landed in another airport. Fun times having a carryon lost on you.
Uh, excuse me - what? If the overhead compartments for carry-on baggage is full - you got plenty of space under the seat in front of you.
The only exception is really if you're by the emergency exits - then you're not allowed to have anything that could obstruct or confuse people when they make their way to the emergency exit.
Well, that came out silly in hindsight - of course there are more options than the overhead compartment and under the chair in front of you.
What I was trying to say is that I've found it unusual that I've not been able to put my carry-on baggage under the chair in front of me and I have not noticed the flight crew having to handle any other options than the two above.
The only reason I don't like boarding last is that sometimes the overhead storage is so full it can be a pain in the ass to fit my suitcase anywhere near my seat, which not only is a minor annoyance when boarding, but can delay me when getting off (if I have to put it further behind where I sit). Generally I aim to be in the last 3rd of people boarding.
There are also budget airlines that don't offer reserved seating (e.g. EasyJet and Ryanair in Europe - I think, I don't fly these airlines though), so priority boarding on them allows you to chose a seat, or to ensure you sit next to whoever you're traveling with.
I saw at least one case where a checked-in passenger arrived around 7 min before the official departure time (he was in a bar) but the gates were already closed and they didn't let him in.
That's a different situation. Boarding time is often up to half an hour before departure. If you're at the gate but sitting (rather than queuing anxiously or even, as some people do, trying your best to board first for some reason) then they're not going to deny you boarding simply for being one of the last people to board the plane. If there's a gap between the queue ending before you arrive, then you're more likely to be denied boarding.
Boarding first or near the first is much better when you end up with a seat near the back, since it means you can just walk all the way through a mostly empty plane, put your stuff in the empty overhead compartments, and get seated without having to make your way through a narrow corridor filled with other people fiddling with their stuff. If your seat is near the door, then the opposite of this advice holds: be one of the last to enter the plane, and you won't have to get jostled around by everyone else behind you walking by. I think if everyone queued up in this order (furthest from door enter first, closest to door enter last) it would make boarding a lot more efficient.
Airlines in the US close boarding 10min before departure (assuming no delays). Once they close the gate door, they are not allowed to reopen it to allow a passenger through
It does in the USA, even if you have a single ticket that has a connection, said connection will leave without you, even if your bag has already been packed on the connecting flight.