Sailor Sakura is almost like a p2w Kimimaro...
If the enemy cannot ignite, she is basically unkillable due to her passive that heals whenever she takes damage. Many "expensive" blitz teams are humiliated by her.
The extra stats from 4/5 star just make her even more frustrating to deal with. The AOE slug goes well with Water's Poison Tai ability or just increasingly obnoxious aoe dmg for any other comp.
She fits into many teams as a healer/tank.