It's funny how you say this is the textbook scenario ideal for DSLs and I see it as the textbook scenario ideal for a real programming language. Organizing stages as a DAG with "transition ruled by a set of rules" is bonkers, I know how to write code with conditional logic and subroutine calls, give that to me.

Wrapping it in a DSL encoded as YAML has zero benefit other than it being easier for a team with weak design skills to implement and harder for users to migrate off of.