I think the question is how you exercise the control you do have, as a parent or proxy.
It's irresponsible, IMO, to wield power simply because one can.
If the goal is to get the child to sleep on her own, on a permanent basis, there are a variety of ways to get there.
One is the authoritarian route, which is basically "because I say so." This shows who is in control, for sure, but also causes a lot of problems.
An authoritative parent/ proxy controls the situation so that the end result is the same -- the child is sleeping on her own -- but more subtly than by just wielding the blunt instrument of "because I say so." This would include helping the child become motivated to sleep on her own, offering rewards, etc.
Would you berate a child for not being able to walk a tightrope, telling him or her that he or she must climb the ladder and walk across the tightrope with no net, no debate, a rule that the child must abide by, plain and simple, cut and dry? Kids often WANT to do things that they don't really know how to do yet. They need to be taught and encouraged along the way.