Ian Jackson has brought this to us :
What you're saying is that late, 'co-operative' mergers force the
'unco-operative' would-be queue-jumpers to 'co-operate'. Well, this is true -
but it often leads to a log-jam at the pinch-point, and that creates
tail-backs that probably would not have happened if everyone had merged
early, and (if possible) maintained speed.

In my experience, yes..