Hi Maciej,
I'd like to respond to some of your statements:
- The Scrum Guide can indeed be experienced as ambiguous. That's because it is "a lightweight framework" and "purposefully incomplete" as explained in the first chapters of the Scrum Guide.
- The rationale for removing those 2 stances can be found in the referenced article of Barry Overeem. It sounds to me that the reason was merely to avoid confusion and make the model simpler.
- Because the scoring on the radar chart is relative, there is no absolute scale. The idea is to assess yourself on what you think is the utmost (=100%) you should be doing for a particular stance and visualize where there is room for growth.