Yup. Same old and tired arguments. Not going to argue with you, as the Internet is full of these arguments. Good to hear that you agree the science of how the beads work is valid. Not sure why you you don't think it applies to any other than big tires though. Tire shops must really hate that an inexpensive handful of ceramic or glass beads can do a better job than their expensive machines.
To answer your question, beads not currently required to correct an imbalance spread out evenly around the tire. Sure, in your example I may have an extra 3/4oz (21gr) of balancing material inside my tube, but since the beads individually weigh a fraction of a gram, they can balance my tire more accurately than the "close enough for that schmuk" tire shop employee ever would. And the beads do so continuously, unlike the fancy tire machine bolted to the floor back at the tire shop.
Am I sold on balancing beads? Yes. Do they work? Yes. Do I care if anyone else will use them? No. Since I never have to pay for balancing, or re-balancing of tires, I'm saving a lot of time and money over my motoring lifetime. That I care about.