Thanks Peter. Your comment about it being an issue of timing and opportunity makes perfect sense. In fact, your framework could perhaps be extended to show phases of evolution. I tend to look at this (social) phenomenon from the perspective of Innovation and the related idea of diffusion of innovations. Just as innovations progress through phases, we are seeing the next stage of their evolution, and the corresponding changes in emphasis and critical roles.

Nice insights Peter! As you suggest, the movements of personnel perhaps do indicate a progression in the field's maturity. I think it indicates a growing confidence in the potential of the paradigm, after the low-hanging fruits have been widely harvested. Do you think it is possible that there might be multi-lateral flows so to speak, as experts try to round-out their experiences with some diversity in exposure and experience ( The ones you list here do not need that!)? Your point about experts having to be well-grounded in business is on-the-mark. The opportunity to realize transformational outcomes, which I believe is often left unexplored, will need people who have deep understanding and the staying power to make the kind of systemic changes enterprises will need to make. Do you believe, that the industry has developed the appetite for taking on the next level of complexity?

Peter - I see you are making a distinction here, using the term 'business' to mean critical to the business. I quite like that interpretation too.