Is GraphQL Querying the Whole Data System?

GraphQL allows you to get data from different resources and one response. You don't have to do lots of round trips, right? You can just ask for exactly what you need. No more and no less. That's exactly for what I'm looking for. Yeah. And then you have so many network calls also, right? So why should we query each resource separately? We want something which queries the whole data system, which carries the whole schema. Right.