Some people don't believe in the cry it out sleep training method here - what's the thinking here?

This is the method that parents give in to when the baby is little older and they know that it is not some physical problem that is ailing them but that's a kind of crying bout. Parents get too tired trying to calm them down and when nothing works, this method does work sometimes. Personally, I have resorted to this method just once. It makes you feel guilty later for letting the baby cry for long and you have to be little more stern that you already may be.