Really?Our world has bumblebees in it, which violate some of those same principles and yet can somehow get and remain aloft.
A dragon in a fantasy world and a 747 in our world aren't aerodynamically all that much different.
One can still wrap those tropes and expectations up in a reality-based setting bolstered by consistent underlying in-setting physics to account for those things that work differently from our own reality. In other words, reality-plus.
All "in-setting physics" means here is we make it up and toss a figleaf/lampshade over it. My setting has dragons. Your setting has dragons plus a page of notes trying to explain how a dragon generates the lift of a 747 despite not having jet engines. This doesn't make your setting more realistic!
And here we see it's not "reality plus" at all.A good and valid question, to which my answer at least is that I can't be arsed to do all the historical research I'd need to do in order to get it even vaguely right.
That, and true historical respresentations would likely run hard afoul of some modern sensibilities. I don't need those arguments.
People fall to earth, but dragons don't. Kings live in castles, but don't extract labour from their peasantry to build and maintain them. Castles are treated by all and sundry as seats of power, although they are not capable of serving the military function that real-world castles did. Etc, etc.
This is an agglomeration of tropes that - from the point of view of actual causal processes that actually operate in reality - is just arbitrary. What makes it non-arbitrary is nothing to do with reality, but rather to do with the folk tales and literary works that it is all derived from.