In general, a relational database provides a fixed, queried, self-describing, lazy evaluated system that is inherently loosely coupled. It's surprising that its perceived to be more tightly coupled than a component based system.
I agree 100 percent with this statement. I think the current popular SQL databases are archaic for a number of reasons, yet they are a mechanism for loose coupling. What's more, they are widely understood by developers. An unfortunate aspect of relational databases is there is typically so much ceremony involved in putting one into production. There is a time and place for ceremony, and likewise for agility. We should be practicing agility with databases, and vendors should be listening for ways to improve them.