It's certainly true. Coupling measures the degree of interdependence between modules/functions/classes. If everything is copy/pasted, no module depends on any

It's certainly true. Coupling measures the degree of interdependence between modules/functions/classes. If everything is copy/pasted, no module depends on any other -- it simply has its own copy of the code. This will result in a terrible system, but it will be very loosely coupled. When you change something, you won't have to worry about it's impact on anything else. In your example, if the content of the file is changing the behavior of the program reading it, then the programs are sharing code via the file. It just happens to be going on at runtime rather than at compile time.