I'm interested in your choice of words here.
This is not about blame. It is not even about your daughter's personal qualities. It is about the reality that learning to deal with nasty and bullying people is a lifelong social lesson.
To try to illustrate, I had a boss who was a terrible bully. She was one of the indiscriminate bullying types: she would (and did) turned on different members of our staff on a whim. I don't think anyone escaped entirely. She lied, she was unfair, she set people up against eachother..
The people she bullied ranged from timid, shy types to extremely assertive types. However, in the dynamic of that workplace, she had tremendous power because our union is weak and at the time it was very difficult to get jobs in our sector. When it was my 'turn' in the spotlight, I tried to involve the union and it caused nothing but stress and I ultimately 'lost' the battle I was engaging in.
Given that she caused the same problems to a variety of different people, it wa clearly more about her than it is about the people she is bullying. However, she was never going to change. I couldn't, at the time, leave my job. I didn't want to. And so the only alternative was to learn to cope with it, get support and sympathy from others in the same situation, and challenge her as best I could when it was important to me to do so (but otherwise try and fly under her radar so to speak).
I left when I wanted to, to go to a better job. By the time I left, I had learned to laugh at her silly power battles. However, I was the one who changed.. not her.
It was her fault, but it was MY problem.. and I was the only one who could change the situation.
It is no different for adolescents. You can't expect other people's parents to solve he situation. They can do what they can, much as my union did, but ultimately, your daughter - like all people in these situations across the lifespan - has to find a path out of the situation that is suitable for her, keeps her safe and doesn't compromise her integrity.
The exception I would make is where a bully poses a physical threat or where it is affecting the mental health of the child who is being bullied to the extent it poses a serious threat. If I had tried my child in counselling to help them problem solve it and they were finding it hard, at that point I would remove my child from the school, in much the same way if it was that bad for me at work, I would leave the job.