Lore reason: because after a major destructive event, humanity was strapped for time and resources; and so converted civilian worker Dolls into combat Dolls.
Business and consumer reason:
VTuber who cheated on her husband with 3 other dude's while he was deployed in the army a while ago and who also supported the Hogwarts Legacy harassment campaign is currently trying to play the victim card; and literally every Western indy vtuber in existence is dick-riding her.