Rationale? How about .... The laws of physics bluntly stating that not only do AFCI's not work, but that they never can - as the arcs they claim to detect simply cannot exist?

Sort of like anti-gravity paint.

http://en.wikipedia.org/wiki/Paschen%27s_law

AFCI proponents have been snookered. It's that simple. Just like the folks who were persuaded that simply turning your headlights on in daylight would somehow, magically, eliminate car accidents.