My key takeaway from Tim Gorman's article is "...what works very well for a CASE application supporting 1-5 developers who think a lot and type only a little may not work well at all for a mission-critical order-entry application supporting 300-400 reservation agents who think very little and type very rapidly. The database workload generated by a small number of users generating transactions intermittently has little in common with the database workload generated by an order-entry application."
Similarly, Oracle also offers a "property graph" database (within Oracle Spatial) which seems to store properties in key-value format. But generally, property graphs are queried much differently than, say, a high-volume data warehouse.
https://blogs.oracle.com/bigdataspatialgraph/entry/from_relational_table_s_to (And yes, I own and have repeatedly read "Oracle Insights: Tales of the Oak Table")