[linkmotif]

This is entirely incorrect.

GraphQL is a wrapper around your service layer, or worse, around a number of ad hoc data sources. That service layer or those data sources may query SPARQL services.

[lolive]

So GraphQL is a graph abstraction over REST APIs, at the cost of massive REST calls to rebuild a graph. True?

[lolive]

basically yes: http://graphql.org/blog/rest-api-graphql-wrapper/

[linkmotif]

You can wrap REST APIs with GraphQL. And yeah, as you you mention, caching is usually important in such scenarios. In JS there's https://github.com/facebook/dataloader which help with the caching. I am using a Java implementation with Google's LoadingCache.