> That doesn't make any sense. Why did uk want to start a fight over icloud E2EE backups (opt-in) but not whatsapp E2EE backups (opt-in)?

Default iCloud backup always included WhatsApp too, even if it was disabled in the app or the app used encrypted backups. And many other things, so it was not only about WhatsApp. Even for WhatsApp alone, it was slightly more useful.