[tshaddox]

Any non-trivial REST API is also going to have responses which embed lists of related resources.

If your REST API doesn't have a mechanism for each request to specify which related resources get included, you'll also be wasting resources include related resources which some requesters don't even need!

If your REST API does have a mechanism for each to request to specify which related sources get included (e.g. JSON API's 'include' query param [0]), then you have the same problem as GraphQL where it's not trivial to know the precise performance characteristics of every possible request.

[0] https://jsonapi.org/format/#fetching-includes