I'm curious if you could share more on the GraphQL part of the situation you describe here, and if being architected on your more traditional "RESTful" (however you want to define that, but usually Rails defaults get you a wonderful implementation of "RESTful") API convention would have made any difference in the performance issues you encountered at Shopify.
We didn't have the same problem with the old REST API, because the requests were naturally sliced by whatever resource type people were requesting. Whereas the GraphQL API allowed clients to request big slices of disparate data all in the same request. If we had (for whatever reason) exposed a REST API that fetched lots of different slices of data and combined them like GraphQL does, those requests would have faced the same problem.
So it was really due to the nature of GraphQL that the problem materialized, rather than being a GraphQL vs REST issue per se.
