> When a collection of such propositions is stored in a computer system, we call it a database.
Is it? A database is a place data is stored and retrieved. It is literally a data base. No more, no less. Whether it logically models a domain may be completely irrelevant to store and retrieve data.
I would argue that a database should not logically model a domain. Why? Because every database must store and retrieve data. Therefore data should be modeled to store and retrieve data as efficiently as possible. And the structure that most efficiently stores and retrieves data most likely does not logically model a domain.