The primary goal of ECS is arranging data in a more CPU-friendly way. The secondary goal is avoiding hardcoding the behavior of your model into a type hierarchy

The primary goal of ECS is arranging data in a more CPU-friendly way. The secondary goal is avoiding hardcoding the behavior of your model into a type hierarchy. As a comparison, imagine your bank's lending products. You probably don't want to hardcode them into a type hierarchy with a virtual method AccrueInterest(Date), but rather have flags that indicate which loans accrue daily, which loans accrue monthly, which loans have some secondary interest etc.