The ultimate focus of a business analyst is client value.
Since context is required to determine value, a business analyst has to have a very good understanding of the context where value will be realized.
In most change, there are increases of value and decreases in value. The change creates improvements for some stakeholders and creates more work for other stakeholders.
It is the overall value that needs to be determined which requires an objective holistic perspective. This perspective will be affected by biases, differing goals and objectives, and different overall visions.
Documentation, especially models and frameworks help all parties gain an understanding and to build alignment.