It's not my fault

Chara is responsible for the events prior to Frisk's journey and the hostility Frisk endured. Had they not went through with their plan Asgore would not have fallen into grief and rage. Six kids would have been killed. And monsters wouldn't have become hypocritical would be murderers. I don't believe genocide is necessary but some monsters do need a good slap in the face for trying to murder a child.