What's with the connection between stat changes and mist/fog/clear body/etc?

[xZippy]

Like, if a pokémon screeches at you and lowers your defense harshly, how is filling the area with mist gonna undo that? Also, how is having a "clear body" magically immune to stat reductions?

 

[Fairy]

Pokémon magic, my dude.

 

[Nah]

Maybe there's not any real reason. Or maybe it's the sort of thing that's derived from Japanese language/culture/folklore and only makes sense if you're familiar with that. But I don't really know.