RDF is a directed graph model. Nowhere does it say properties have to have properties in a graph model. You can always model them as intermediary nodes.
Using intermediate node is changing the structure of the graph. RDF is not a general graph model. The fact that a node cannot hold data by itself (a link to literal is required) is risible.
Naming of nodes with IRI is also a ridiculous, especially in Linked Data where changing your hosting domain (and even the protocol to access data) requires changing the data itself.
Are you kidding? IRIs is what sets RDF above and beyond other data models. Global identifiers are crucial if you want to work with data interchange on a web scale.
Show me a definition of a "general graph model"? Nothing shows up on Wikipedia.
You can have global identifier without IRIs, for example using GUID (that’s the solution used for COM components for instance).
The thing is you can’t represent "A"->"B" directly in RDF. You need to stretch the representation to at least use a resource node as subject, but also for the object too if this node could be used as subject in another predicate. And of course both these resources must be encoded as IRI and then linked to the literals that contains the data. That’s four nodes and three links instead of two and one. It’s a lot of boilerplate code for a simple problem. And as said before, putting key:value on an edge require reification of the edge... which undermine the simple SPO model because it’s now SP(O as P)PO.
You may think it the same but it’s not. Usability matters and that’s why the SemWeb stack has almost zero adoption since its inception while graph databases are trendy.
Naming of nodes with IRI is also a ridiculous, especially in Linked Data where changing your hosting domain (and even the protocol to access data) requires changing the data itself.