They are an abstraction that will save code and bugs, and introduce strong conventions.

The DSL has a weaker control over the program’s flow — we can’t have conditions unless we add a special step

Using a terminus to indicate a certain outcome - in turn - allows for much stronger interfaces across nested activities and less guessing! For example, in the new endpoint gem, the not_found terminus is then wired to a special “404 track” that handles the case of “model not found”. The beautiful thing here is: there is no guessing by inspecting ctx[:model] or the like - the not_found end has only one meaning!