alt Hacker News>with no good way to get back in.
which is why at the very least your email provider gives you a recovery kit to print out (the equivalent of the notebook) and if you can get back into that account you'll likely be able to get into whatever else you signed up for.
There's no difference here between passkeys and any other central storage be it a password manager or a physical notebook. If you lose that access, well you're screwed. But it always beats having hotdog123 as your password for 70 different sites.
Password managers can be backed up onto USB drives pretty easily, and copies can be made of paper.
It's much more difficult to make comparable backups of passkeys due to all the "anti phishing" / vendor lock-in rules most platforms have.