Convinience is a key part. Let’s say I have bought a new device and have 50 accounts on different platforms. The way I’d do with only passkeys is that you would create 50 different keys individually for your new device, using a device that has logged in.

Password manager? I download a keepass compatible app, have it connect to my FTP for its database, enter my unnecessarily long key word or a random file i store seperately; and now I can access to all of my accounts.

As long as I do not somehow get both my database and its key word/file leaked at the same time, my accounts are as safe as whatever passkeys can provide.