In a past company I worked in a department that does not traditionally have project management. When I joined the department it was just crossing the chasm from one off to repeatable. Working with the existing team I helped map out the entire end to end process. We came up with a RASCI chart of over 1800 distinct line items in the release process, with the PM being involved in over 90% of those. We boiled this down into a phase by phase process document, with about 200 core task areas that the Project Manager was directly responsible for.
Now this was great and detailed. Just showing people the RASCI would cause jaw drops.
As an added bonus, fast forward a some time and some politic shifts later, our department was cut during a major restructuring. Functional Managers had argued they could do the job in addition to their normal job.
Now they had our very detailed process document. They had step by step instructions on what do do, right? It should have been easy, right? With in a month of our department being cut, they were underwater trying to figure out how to do all the work we did, even with the process doc.