I think the idea was that the whole 'loving authority' thing was really only necessary for those that had strayed off the path - in Marston's world, all the GOOD little boys and girls understood this stuff instinctively; it was only the bad guys that needed discipline, to make them see the light. Otherwise, she'd be chaining up every single person she met - and regardless of Marston's excesses, he didn't go quite THAT far.