I think there's a general understanding that, all else being equal, people get of an aeroplane from front to back. Therefore, it's fairly normal for people standing up to let people who happen to have been sitting in front of them but not already in the aisle get up and get their bags and continue down the aisle.

Not everyone wants to stand up for five minutes or more in the aisle after the plane has arrived at the gate (and some people are more or less prevented from doing so, either by age or infirmity, or because they can't get out of their seat because of other people being in the way, or whatever).

I, on the other hand, normally do aim to get out of my seat as soon as possible after arrival at the gate, simply to stretch my legs and avoid claustrophobia. But that's a personal choice. I don't think that this means that people sitting in front of me who don't do this should have to wait for me to go past them before they join the general exodus.

Aeroplanes are not overly blessed with space, generally, so everyone has to make some concessions to other passengers.