It is pretty relevant actually.
Because, as the original poster stated "Just because you stumbled across a single application server that can do that doesn't mean it's true for GraphQL in general."
In general, when talking about most graphql applications, that people use, the original statement is true.
So the original statement is true, for most people. Which was the other person's point.
I'd note once again that the statement was "in general".
Usually, when discussing large frameworks, and technical issues, that effect many people, we are mostly concerned with how it applies to the vast majority of people and applications.