It wasn’t her quirk.

It seemed to come with some serious distortions to her animal drives.

Where “normal” people might feel the urge to hug people they like, Toga had a base desire to consume the blood of the people she liked, and literally become them.

If all her quirk was that she can transform into people by consuming somw of their blood, people would go “huh, neat” but she was incaoable of functioning socially in a way society at large would have considered normal.