(Yeah, so do I. I know it's a kid's show, but it came out of the blue. I should show you this fanfic I read that had an interesting theory regarding that: http://my.deviantart.com/messages/#/d2st04l It makes the spirit bending look a lot more sinister. )

Granted, it's probably only the Avatar that can spirit bend. However, it wouldn't surprise me if the anti-bending group did some research into how to remove bending. We know Ty-lee can temporarily, so...