Meeting abstract versus full paper

JACI has an interesting letter comparing the number of meeting abstracts and the subsequent publication of a full paper. It seems that there is a large variation from from 11% to 78% – does this really mean that at some meetings half of the talks is not worth to write them up? This would explain why at some conferences nobody is taking notes – I am usually playing sudoku, backgammon or go but have also interesting podcasts with me.