2d platformer: Why can't Ellen deal damage to enemy by squishing it?

Hi, I'm new to Unity so my question might be elementary. In the 2d platformer kit we are taught that any object with a **damager** component can deal damage to an object with **damageable** component. Fair enough, but since the main character Ellen has a **damager** component with the hittable layers include the **Enemy** layer, why can't she damage the enemy by jumping on it and squishing it instead of a melee or bullet attack?