I would say they are useful, specially against a relational database, when you have a ever-growing or dynamic amount of different entity types that are all related between each other. With a knowledge graph you only don't need to create new tables every time you define new entity types, you also can give semantic meaning to the relationships between them.
Offtopic: I'm seeing a trend of titles that, as a non native English speaker, always confuse me and take me a good couple of seconds to finally understand. This is one of them. It's like they use a comma where I would expect an "and" to be. I wish I had more examples to show, but I have seen a lot here in HN. Is this some new editorial style or was this always used?
When you write a list of items, such as, "one, two, three and four", you use commas instead of "and" or "or" between each of them except the last so people know whether the rest are "and" or "or". In this case, "or" doesn't make sense so the comma means "and".
It’s a common style of telegraphic English used in headlines. In normal prose we would write “handcuffed and jailed”. I don’t think the style is new. In fact, as a native speaker, I also sometimes have to read headlines three times to figure out what they mean.
