No complaints with questions, but many of the questions are in the form of assertions that are incorrect.
"Does that mean that passkeys can't be shared between users or devices?" is a 100% reasonable question.
"Passkeys are a step backward because they can't be shared between users or devices" is not really a question, it's an opinion based on imagination.
And passwords are just as complex. How do you securely share a login with another user?
Yes, there's complexity, but it's complexity born of a change in paradigm. The actual new thing is either equally simple or simpler than traditional passwords, once you factor in scenarios like backup, transfer, multi-device sync, sharing, etc. It's just different.
One counter point though is that... if there is a new lifesaving technology, and even the somewhat IT literate / somewhat geeky / folks who WANT to understand it, are struggling... it may not be as simple and easy and safe. If I ask "how do I backup my passwords", I'll have 10 million folks answer "use a password manager, backup the file". When I ask similar questions with passkeys, the breadth,inconsistency and complexity of answers is as insightful as it is worrisome.