Steve Walker brought next idea :
whereas merging at the pinch-point often means cutting into a small gap,
causing those behind to brake and the ripple effect to bring the whole road
to a halt or slowing to a stop yourself and holding up the traffic behind.

Not if the merge is orderly and with cooperation from both lanes, which
is what you get as a result of no one being able to bypass the queue.

Early merges, leave one lane less than fully occupied and space for the
impatient to bypass the queue.