I really believe this position should be reconsidered.
If I want to do the following as an example.
I have something like Skill as a node.
This can be linked to many other things like Course, Job, Person
I don't need the models or Course or Job or Person to be aware of the relationship with Skill. and I don't want Skill to be modified when a new kind of relationship is added. I want to manipulate those relationships by themselves like I could with OGM and RelationshipEntity. By forcing ownership I am now forced to load the relationship or use projections to avoid loading the relationship and forced update the class with @Node as the owner of the relationship when adding a new kind of relationship.
With RelationshipEntity I had a way of adding and querying a relationship without updating the NodeEntity until I decided I wanted that relationship as part NodeEntity.
With SDN 6 I cannot manipulate arbitrary relationships. I have to go to CypherDSL or Neo4J OGM or core Neo4J API.
I always thought that Nodes and Relationships have the same value and standing.
This approach turns Neo4J into a Document database.
If there is something I am misunderstanding I am open to being shown the error of my ways.