It seems stackers aren't zapping what they might once have zapped because they don't think it will have a payoff or they are zapping content they wouldn't normally zap in order to increase their zaprank. In short, it's become a little more transactional.
I deny. I am not doing it that way nor I am being so much over-stressed with the MSM. May be that the behaviour of stackers have changed a little due to MSM but it has definitely brought the madness back. Or, correct me if I am wrong, we have witnessed some of the best content on SN only largely because of MSM.