Yes, yes, I’m well aware of how it works (I’m a former traffic engineer IRL). Although it’s true the behaviors trigger the slowdowns, it’s the traffic volume that creates the conditions where switching to the congested flow regime becomes possible.
In other words, if high traffic volumes aren’t present, those behaviors don’t have that consequence, and moreover, if high traffic volumes are present, the free-flow regime is such an unstable equilibrium that some kind of event (even one as minor as a driver briefly tapping their brakes) triggering a shift away from it and to the congested regime is inevitable. It’s the volume that’s the essential condition, not the behavior.