I'd point to Datalog and Datomic as interesting touchstones. CSS is also very interesting as a query language — it's declarative, high-level, and at an interesting place in terms of abstraction vs concretion. There's a lot to be learned from comparing and contrasting all of these different approaches to query.
What follows will be some off-the-cuff conjecture. Caveat emptor.
The thing to look at, between SQL and GraphQL/Falcor and Datomic/Datalog, is what underlying principles inform or support the design of the language model. SQL is strongly rooted in the relational algebra, and so as a result you get all the fantastic properties of set theory. Datomic/Datalog are designed around the mechanics of predicate logic, so your queries are logical expressions fed to a constraint solver. GraphQL/Falcor/etc are not rooted in set theory. They're not really rooted in any underlying logic, one could argue. They were designed to suit the structure of React, and not to surface the power of set theory (or any other algebra) in a programmable way. The fact that GraphQL leaves relationships, sorting, filtering, etc up to the implementation is a symptom of a missing underlying theory.
What would be nice to see is someone taking the lessons of GraphQL, like the power of allowing for partial evaluation of a query, and applying this to a query language engine with a richer set of underlying semantics. There was a tiny bit of this attempted by David Nolen with Om.next, but it never got off the runway.