> The author advocates starting with database design before software. Some other people advocate the opposite: the database is just a detail.

If the database is just a detail then you most likely are working on a small toy project. Or a class project. If it is a significant project where performance, scale and security matter, then database is the central concern. You have to start and end with the database. But dealing with data can be boring and cumbersome so we tend to jump to coding and proscrastinate on database and data design.