No, I am saying that if you as a DM have a player that wants to play a Dragonborn and you can not (or will not!) fit one into your world then you are a Lazy DM.
How would you describe this "hypothetical" DM?
I have looked, long and hard, for a way to fit Dragonborn in my world. I am on the cusp of getting them worked out as a culture, but they were previously unplayable. If a player has wanted to play them, I would have said no. This world has been entirely my construction, and I cannot shove a random Dragonborn in just because a player is feeling entitled. I have been lucky enough that they showed no such interest yet, so there was no such confrontation.
to describe such a DM is situational. In my case, I have slowly built my own world, from the ground up. My players specifically refused to help in any way, saying they just wanted a world to play in, not put work into making one. I would describe myself, and a DM like me, as perfectly competent (in that particular area at least. My competency in other areas is questionable). It is a different discussion of it is a published world, and a players
absolute favorite race is Dragonborn. then there is a reasonable argument for including the race against the DMs preferences, IMO. At that point, a description is pointless, as the situation either works out, or it doesn't. Either side could be labeled as lazy, obstinate, or childish, by the other.
My point however, is that simply not including a race is not "laziness", by necessity. There can be any number of reasons for an exclusion or change, and if it is not a players own world, I don't see why they would get the trump card to choose what does or does not belong in it.