Phantom
Uh, I didn't do it.
Wait, what? I'm confused now.
I think what Light's saying is that you never know how someone's going to respond to discipline, and that if it's either no discipline at all (in the case that nothing else works prior ie grounding or something to that end) or spanking it's better to have been spanked and risk it then never to have any sort of discipline work at all.
Which makes a little sense, sick as it is.