Given all the ambiguous reasons and moreover the lack of solid reasons as to why and what method to use while fogging I'd have to go with the manufacture of the motor.
Dry vs wet intakes
Cats vs no cats
No clearly defined reason as to either methods or equipment puts most of this up in the air as to why we do it they way we do it.
I have my own theories to support why I do it the way I do it but I generalize those theories based on what Indmar says is the "right" way to do it.