Well it's not so much a difference of opinion, it's a matter of whether the difference should change much!
This is a good explanation:
http://visual-vacations.com/Photogra...pose_sucks.htm
The real problem I have with it, is that it takes a very carefully constructed scenario (Unusually close photographer with a wide open lens with a significant recomposition) to construct a scenario that demonstrates the problem. My response is that, well, with that narrow tolerance without putting the critical point right on an AF point, you're likely to screw the pooch anyway, so you have to ask yourself if you really NEED to be in that situation, with such a narrow DOF.
(For example, what he kindly neglects to point out, is that for the scenario he constructed with a 100mm lens from 6 feet on a crop body, your entirely field of view is only a little under a foot and a half across, so if you REALLY did what he described, you'd have a nice slighly out of focus shot of just that girl's bust.)