It's an opinion based on countless of references and books out there. I cannot cite them, but it's like "code should be designed to depend on abstract interface

It's an opinion based on countless of references and books out there. I cannot cite them, but it's like "code should be designed to depend on abstract interfaces instead of a concrete implementation", "everything is a byte stream", "adding more people to a late project makes it later", "Bad programmers worry about the code. Good programmers worry about data structures and their relationships", "Show me your flowchart and conceal your tables, and I shall continue to be mystified. Show me your tables, and I won't usually need your flowchart; it'll be obvious.", etc... they are usually true.