> probably you would use the same query for a Graphql resolve

When you're hand-writing SQL for a specific client experience, you can make optimizations that GraphQL cannot make because you have knowledge about the constraints on the information in the given context that GraphQL doesn't have. This is a tradeoff that comes with querying information in a generic way vs. querying information in a way that is specifically tailored for the experience. As a result, you often end up with queries that are faster than can be assembled by GraphQL.