We see Neo4j get used relatively frequently as the aggregate view of data pipelines, e.g., Roam Analytics uses Neo4j to spit out tables/views across many different data sources to perform ML enrichment on that they then pipe back into the graph to feed their app.

eBay (ShopBot) is a Neo4j powered ML chatbot. AirBnb also builds knowledge graphs with Neo4j.

Video from GraphConnect today talking about knowledge graphs: https://youtu.be/dqrlotzdUlo?t=3175

Transparency: I'm an employee at Neo4j.