This means if you go on a trip somewhere you absolutely need two devices. If you kill your phone and want to buy another one ASAP, you wont be able to do anything with the new device until you can convince the platform it's you. With passkeys you're just SOL. Imagining if you needed a phone to get back from your trip - e.g. etickets, auth needed etc. - it becomes a nightmare scenario.
A third party manager makes it easier, but it's a lot less usable that the first party ones.
Reasonable people make different life choice, having to constantly think about backup strategies whenever I'm away from home would be so stress inducing to me.