Since the introduction of table witnessing at my old hall, publisher hours and placements slowly declined. I think your on to something here. Nobody wants anything to do with the trash they are trying to sell and so the witlesses are becoming less active. As with the doors, they see for themselves the sheer number of people who are just not interested in the message.
For myself, before it was over I seen no reason to preach. It was a waste of time. Nobody cares what those stupid magazines or books say. And most people by now realise that the dumbs are a cult.