Fair point about the DB scaling but not sure if everyone is going to run into this issue. Also, lots of solutions are emerging for this specific problem (with different trade-offs of course) like distributed databases (crunchy, YugaByte, Spanner, etc.). Most folks I work with get by with a reasonably sized DB and some read replicas.
Not a GraphQL problem though IMO.
While you are correct, not everyone is going to end up with this issue, those that are thinking of getting to a medium sized business should be working to avoid it, which unfortunately means solutions such as hasura lose value. It would be good to see more ability to collect data from multiple sources (please reply and correct me if you already do this, I'm not super familiar with the service).
Sources can be databases (postgres family, sql-server, big-query currently, and as we add support for new databases) or REST APIs or GraphQL APIs.
This composition allows in a final GraphQL API that federates across different sources.
From our docs: https://hasura.io/docs/latest/data-federation/data-federatio...