Yaml is straightforward. But in the case of ansible yaml is just the concrete encoding. The author's grievance seems to come from the fact that they would prefer to invoke commands directly as python, instead of having ansible translate yaml to python. I do not know if ansible gets any significant benefits from the usage of yaml (maybe restricting the available functionality for better safety?), but I can totally understand the issue from a user's point of view (I am using robotframework quite often).