>I'm personally of the opinion that "graph databases" should be relational databases; the relational model can subsume "graph" queries

The MIT team which is also part of the team that proposed GraphQL already kind of solved this problem using D4M [1].

Essentially D4M is able to universally represent relational, graph, spreadsheet and matrices using the mathematic technique of associative algebra, they even wrote an entire book on the subject [2].

It's beyond me why they didn't push forward for D4M but instead propose a limited GraphQL. It seems that they're restricting the D4M capability and focusing on query language like GraphQL, perhaps due to the industry demand and bias.

Heck the same team also proposed TabulaROSA, a new database OS as the more efficient alternative for conventional file-system based OS like Unix/Linux [3].

[1] D4M: Dynamic Distributed Dimensional Data Model:

https://d4m.mit.edu/

[2] Mathematics of Big Data: Spreadsheets, Databases, Matrices, and Graphs:

https://mitpress.mit.edu/9780262038393/mathematics-of-big-da...

[3] TabulaROSA: tabular operating system architecture for massively parallel heterogeneous compute engines:

https://www.ll.mit.edu/r-d/publications/tabularosa-tabular-o...