I dont think we are overlooking it. It pretty common knowledge that one has to chin tuck and get in proper body position to get all the mewing benefits.

@adam I didn't mean chin tuck though, i meant raising the sternum closer to the chin.

I think it is important and not just to facilitate Mewing, but because it’s always right.The whole shoulder girdle is important. Walk like a Cretan Shepherd. Further release the muscles of the neck, at the back and the scalenes right down to the pit behind the clavicles. Release the trapezius to achieve shoulder width. Look at people and see if you think width there corresponds to width in the jaw and face.  I find the Wahl massager very useful for this. Also when placed at the occiput it sends vibration throughout the face and jaw. This is helpful to achieving movement.

Posted by: @wickedfinger

Are we overlooking sternum position in relation to the skull?

Just the act of bringing the sternum close to the chin, makes it drastically easy to mew.

No one's overlooking anything, the sternum pulls on the hyoid bone which pulls on the tongue, it makes sense that that inferior hyoid muscles will make mewing harder.