A real need for a project Grand Poobah

Yes, I'll say it, in a book for the whole world to see: in a large program, with matrix organization, there may be a need for skills that we might dub project coordination. Imagine a program of 300 plus people. replace with "Who is responsible to facilitate the creation of teams?" For organizing teams cross-functionally? Who is responsible for communicating with vendors to plan and track deliverables? Who works with HR and finance to budget for and procure resources? Who facilitates the Scrum of Scrums meeting? In other words, when the group is larger than three teams, someone should be in charge of keeping all the dogs pulling the sled in the same direction. Not responsible for the product's success in the market (I believe that responsibility lies with the product owner no matter the size of the program) but responsible for coordination, for getting the whole thing rolling to some cadence, some sort of schedule, and promoting and allowing for change...