You can ignore some of the details, but you can't ignore everything. Which database you choose and how you scale it will affect your application code. You can

You can ignore some of the details, but you can't ignore everything. Which database you choose and how you scale it will affect your application code. You can't write code that makes use of the local file system (or in-memory data for anything meant to be persistent) if you have more than one container serving your app. (And yes, some people need to be explicitly taught not to do that.) And so on.