When you consider the project to organize a simple room, often a single point of view is enough to decide which organization to settle and how to organize. Then, anybody is able to tackle the problem.
When you consider the project to design a full flat, you need to collect and concile the points of views of all people at stake : you, next occupant if you sell it, others sharing the same building, housekeeper, people in charge of maintenance, and so on…
It won’t be only a matter of connecting all requirements, which is not often simple, you ‘ll also need to prove that your design give a response to each of them.
This is the Enterprise Architecture deal.
The deal begins with a single projet. Already you have to contemplate how to be integrated within the whole enterprise computing system.
It continues at the domain level where you try to optimize projects according to delays, resources, costs and quality. Which approach for which target for which stakeholder ?
Do you think it ends with the whole enterprise needing to be properly governed, even regarding technology and systems ? Not at all, since you are within an industry area, which shares resources and processes for B2B.
All these people have differents requirements and need different points of view of the system to be able to prove that it complies with their requirements.
Then Enterprise Architecture is a matter of models as well.