Often is about developers trying to make their systems flexible. In software. You can make any part of a system flexible. You can make several parts of a syste

Often is about developers trying to make their systems flexible. In software. You can make any part of a system flexible. You can make several parts of a system flexible. But the more flexibility you add the less maintainable the code becomes, and there for the least flexible overall. So you really have to choose where do you want that flexibility. Often is better to keep your design simple and clean; and add the flexibility when you actually need it.