While this is technically true, in the SQL world this requires wizard level skills that most SQL developers do not possess, and when you arrive at this spot, you end up with a query that performs really, really badly.
Look, between the database formalisms, they're all "complete" in the sense that you can choose any database and solve all the problems. But certain databases are going to be pathologically bad at solving certain types of problems, which is why there are so many sub-niches that persist over time.
For deep path traversals, you can do it with RDBMS, but a graph DB is going to win every time in part because the data structure is just set up for that purpose. There are other queries where RDBMS will be best too. So it goes.
You can do this with a recursive common table expression.