That's what I mean by not providing a resting place for the incoming force. In order for the path you describe to be effective in grounding the force, the point of application of the force must be "open" in order for the force to travel along the path and be grounded. Locking up the point of application will prevent the force from flowing along the path resulting in a clash of forces at the point of contact.
almost forgot to chime in here. when you let the force going through you to the ground, eventually, with enough force applied, your body would loose its coherency. some of the experts have mentioned to not let the force come into your body. what if you bring the ground to uke's shoulders when he/she/it pushes on you? wouldn't that creates a backlash force within uke's body instead of you, and uke's applied power would push he/she/it away? just a thought.
i have experienced that expert folks can reach further than uke's shoulders.