I'm not sure to get the point. If you are relying on a tool to reach your end goal, you should be as familiar as needed for your purpose. I think the more you w

I'm not sure to get the point. If you are relying on a tool to reach your end goal, you should be as familiar as needed for your purpose. I think the more you will rely on the tool, the more you should know it's inner workings. For your filesystem analogy, if your Python app uses the filesystem as a storage layer you should be clear about the features you expect. When a DOS user will come telling you his data is not stored, you'll have to explain you use long filenames with non compatible characters. And perhaps symlinks for your folders, or access control for user management. And suddenly "just store my data" is not good enough, you'll have to care how and with what limitations. For any abstraction you heavily rely on, eventually you'll have to understand where it leaks.