Don’t you see?? That’s greed. Why do you need their magic? Only to fight them and each other better!

There’s nothing to be gained by keeping them around, they are just predators of sapient people. Their magic is made to dominate and kill

Frieren has the raw strength to dominate and kill, but she doesn’t value that kind of magic despite her skill in it. She wants to create fields of flowers, she seeks beauty instead of violence. Her violence isn’t about genocide, it’s about protecting what she values