[nudpiedo]

All of them are in fact graph databases, they just didn't realize about it and got lost giving the implementation the category of design for many reasons specific to the context in which they were created. I think we should think more often as mathematicians and a little bit less as "hackers"

[TheMiller]

I think this is a mischaracterization. The relational model which motivated relational DMBSs is based on predicate logic. Mappings to graphs are obvious, but are not the organizing principle. This was one of the strengths of the relational model, encouraging a more flexible view of the data than graph databases had previously offered. In a complex relational schema, you can discover and work with all kinds of implicit graphs that were not originally intended by the schema design.

[edmundsauto]

If they are all described as graph databases, we lose the usefulness of understanding the differences between them. I think understanding these differences are at least interesting, and possibly useful.