[@Cyclone] I agree on the point that there aren't enough weaknesses for the scales (And the supposed weakness in fact may act as a strength) and should probably be made weaker than mithril to physical force to compensate for its higher levels of heat resistance. (This in-universe would also explain why dragons aren't just curbstomping everything, since the creation of cannons would seriously threaten their continued existence)

however I don't really see you argument towards plausibility of dragons carrying any real weight, or even being hypocritical. If what you are saying is true, then the fairies should not have been allowed on similar grounds (Being realistically absurd), as well as my naga for being essentially genetically impossible.

And that's not even mentioning the obvious physics breaking technology we are already using, like the flying air dreadnoughts, or the just plain impractical like the land dreadnoughts.