Hey, as long as you don't have a dragon in a world without them I won't complain. If you state your world doesn't have them and you put them in I may look at you funny. Unless you mention they've passed into myth and legend. It's all a game of technicalities for me.
I write what some might call magic realism, so a dragon appearing out of nowhere when it's appropriate is actually fair game to me.
It doesn't matter if dragons are supposed to exist or not. It only matters if there is a dragon or not. It only matters that a dragon makes sense.
But that's not your normal SFF, no. My technicalities are karmic rather than logical.