Business Architecture - Enterprise Architecture

It's a difficult to understand the entire enterprise architecture process in one go, which is surprising since we architects really like our diagrams. Both TOGAF & Zachman framework use visual depiction of information heavily to get their ideas across. But how does one go from the highest level at the business level down to the lowest level of technological implementation? Most organizations don't really ever get down to this level of follow through, after all, why would you need to see what data element in a certain database is used by what business user to accomplish what task? actually... if you think about it ... you might. Imagine an environment where you have had people writing code from before you were born, I was born in 1980, I can actually find cobol programs that were released into the production environment at that time and the amount of business sprawl present in such an organization. But that's a different topic, getting back to the main idea, you need to know who does what in your environment and why they do it, it's just like personal organization, if you always keep the same thing in the same place it's easy to remember where to find it when you need it, you are the architect of your own life.
But since you live your life, you can get away with being sloppy, imagine if different people had to live your life, how difficult would it be for them to find out what you did, why you did it and where you put things you needed? Sorta like that show "Quantum Leap", the guy jumped around different people's body's in different time periods and lived their life for a day. He often had trouble reconstructing what he needed to do. But that's science fiction, there is nothing fictional about the problem organizations face when people leave and new people come in to do their jobs. This is where enterprise architecture can work as a guide of some sort. Business architects are supposed to have diagrammatic representations of the tasks performed by different roles in an organization. These diagrams link the person to the task they perform to the software they use to the data they look at and at the highest level to the goal they want to accomplish. This is the real power of enterprise architecture, a holistic view of the organization that leaves very little to the imagination. The benefits start showing up once you have all this data accumulated and properly tagged. You can start looking at the kind of redundancies present in the organization and how to start reducing IT sprawl. This kind of pruning is not easy, once architects get involved in the day to day activities of their organization its very hard to take a step back and view the data in a holistic sense. This is where lots of architecture programs stop showing value.