Now that would "seem" like a logical assessment of the situation, but you can answer your own question by asking yourself: where does all of the heat go when using the rim as a braking surface?
What would happen to the integrity of the rubber on the bead of the tyre?
What would be the outcome?
Now I think you exaggerates a little, the heat generated when braking can hardly destroy the tire. The surface area of a 26 inch rim is much more than an example. 8 inch disc, much larger surface area to warm up. Only problem with the V-brakes as I see it, is that the rim must be replaced periodically due to wear and tear