Well for starters they can improve your security posture. In proper dbs like PG the version change is transactional so you don't have to deal with schema being

Well for starters they can improve your security posture. In proper dbs like PG the version change is transactional so you don't have to deal with schema being out of sync with code. You don't have to plan for all the possible future scenarios where you will need transaction boundary to cross the service boundaries. You can write stored procedures in pretty much any lang. Query optimisers and execution engines are far more tested and preferment vs some GraphQL gateway.