Earlier quoted context omitted.
At this scale, there are no guarantees of anything. There very likely will be unique copies in there. If these were expert archivists a lot of damage could be prevented, but given the malice and indifference of AI companies, there very likely will not be an expert archivist involved, and unique copies will be destroyed unceremoniously.
My personal wastebook at home is so rare, it's unique. That doesn't mean it needs preservation.
Like did Icelandic author Þórbergur Þórðarson ever write an a book about Esperanto, and send the only copy of it to Halldór Laxness when he was in Los Angeles? I don‘t know, but it is certainly something he is likely to have done. If such a book exists it would be invaluable to both Icelandic culture and to Esprentists. It likely would have stayed in Los Angeles where nobody would know the significance of it until it ended up in an estate sale, a used book store, and then finally destroyed by an AI company never to be discovered.
My hypothetical is just one of trillions of possibilities. At this scale very likely several of these possibilities will unessiseraly remain unknown unknowns forever.