If you build a state machine on top of a relational database you can abstract concurrency problems away from your business logic and allow developers to write safe-by-default code without dealing with concurrency concerns. This post explains how to build a library that offers those protections, and how they work under-the-hood.
That's besides the point. Of course that the most fitting way to represent a state machine is with a state machine. The point is that implementing the transition table in a database table creates many problems while apparently solving none.