[wrs]

Because it solves all sorts of other problems, like having a well-defined way to specify the schema of queries and results, and lots of tools built around that.

I would be surprised to see many (or any) GQL endpoints in systems with significant complexity and scale that allow completely arbitrary requests.

[mattmanser]

OpenAPI does the same thing for http requests, with tooling around it.

With typed languages you can auto-generate OpenAPI schemas from your code.

[wrs]

Yep, OpenAPI is also a good choice nowadays. That’s typically used with the assumption you’ve chosen a supported subset of queries. With GQL you have to add that on top.

[lkbm]

Shopify's GraphQL API limits you in complexity (essentially max number of fields returned), but it's basically arbitrary shapes.