I’m not entirely sure that I do.
I’d challenge the reliance of objectivity within the design process. Design must serve a purpose but I believe it must also mean something to the designer.
As designers we use process models to simplify and to refine what we do, but if we accurately map how we work, our actions rarely match the model. The design process is not an absolute; as it has to remain flexible to the user. My own design process informs my work, and in turn my work informs my design process. Without that two-way relationship we become just facilitators of the model. I think we are more than just facilitators.
Objectivity is important, but not all-important. There needs to be space in the process to allow for our intuition and our experiences to add both value & meaning.
I have studied many process models as part of my Masters Degree research and I am continually fascinated by the differences in designers approach to work. It is in creating these differences that subjectivity is much more useful.