When your data lives inside an application, the application owns the relationship. It decides how your things look, what you can do with them, and whether you can leave.
The separation
Three layers, loosely coupled:
- Data — yours to move, verify, protect
- Interface — replaceable when a better one comes along
- Infrastructure — swappable when the technology moves
Your data outlasts both interface and infrastructure, because it was never the application's to begin with.