Having a little experience in Chinese arts, I can't form an opinion on rooting within them. In my current studies with a Japanese art though, we do something similar by relaxing the body and letting it "sink". Two of the ways we use it are to keep from being thrown (hip throws) or to keep from being picked up.
Both of these don't require the person to be any any stance or to resist with equal force. Most newcomers have a hard time with it simply because they can't fathom relaxing instead of tensing up for it.
I'll admit also, there isn't anything special about doing it. It basically comes down to relaxing so as to break the other person posture (both externally or internally).
