Logically, I agree with everything you've said. However, with a bunch of reading I did when this whole ring thing came about for me, I found lots of contradictory information from other "reliable" sources (of course, I can't remember where/what I read specifically). All I know is I'm going to pick up a set of rings, and see if the minor vibration I have goes away. I'm coming to the conclusion that the ONLY thing rings do is to minimize vibration by helping to center the wheel just a bit better.
EDIT: Additionally, I wasn't talking about bearing the weight of the vehicle, I was referring to the installation of the wheel and that the wheel should be bearing on the hub to stay centered while tightening the lugs, rather than depending on tightening the lugs to center the wheel.