This is more like me picking up a bottle you tossed out of your car and using it for some purpose.
To stick with that analogy, it would be like you sticking a very thin pipette in every coke can in a 7/11 to grab a few drops of soda from each, so you could drink for free.
These little devices are parasitics, if there are only a few, sure no problem, we can’t measure the extra cost at each transmitter or the weakened signal at every receiver. But the tech is so cheap there will not be just a few of them.