Having an interface let's you introduce versions or alternative implementations easily, this is important in a long run. It's much easier to handle the transiti

Having an interface let's you introduce versions or alternative implementations easily, this is important in a long run. It's much easier to handle the transitions, because you can have both versions in your code base and you can easily switch back to the old one if necessary. When you start with a class and you want to do similar thing, you either YOLO it and change everything at once, or you need to introduce an interface and replace every usage to use the interface to achieve a safer transition and you are back at the interface-class implementation with an extra pain.