I think you’re there with the last bit of your comment. The goal isn’t to only move once, the goal is to minimise stops and starts. If everyone does this is a self sorting system. If someone has the rule “try to only move forward once every x minutes (unless you are at the front or the queue overflows)” then the queue gets into a rhythm that works.
In a queue like this there is extra effort in picking up your bags and stopping so the worst case scenario is everyone moving exactly as space is available.
Problem is that “unless the situation doesn’t allow it” means you have to constantly be aware of how the situation is evolving, so you’re trading “move your bag a couple extra times” for “stay hyper aware of the environment and ensure you’re not starting a chain reaction of assholery” cause that can happen real quick at an airport.