What were those "massive problems"?

Re-imaged, lost, or bad updates on PCs wiping out a all the saved passkeys and being locked out of all accounts during off-campus sales or design meetings.

Making staff look like idiots in front of clients is a resume-generating-event.

I'm not the OP, but I expect it the same issues that have stopped me from using passkeys now.

His reply does give one aspect of it: passkey's are fragile. To be secure, they can't be copied around or written down on a piece of paper in case you forget, so when the hardware they are stored on dies, or you lose your Yubikey or is as he described the PC re-imaged, all the your logins die. That will never fly, and it's why passkeys are having a hard time being adopted despite them being better in every other way.

Passkey's solution to that is to make them copyable, but not let the user copy them. Instead someone else owns them, someone like Google or Apple, and they will do the copy to devices they approve of. That will only be to devices they trust to keep them secure I guess. But surprise, surprise, the only devices Apply will trust are ones sold to you by Apple. The situation is the same for everyone else, so as far as I know bitwarden will not let you copy a bitwarden key to anyone else. Bitwarden loudly proclaims they lets you export all your data, including TOTP - but that doesn't apply to passkeys.

So, right now, having a passkey means locking yourself into proprietary companies ecosystem. If they company goes belly up, or Google decides you've transgressed one of the many pages of terms, or you decide to move to the Apple ecosystem again you lose all your logins. And again, that won't fly.

The problem is not technological, it's mostly social. It's not difficult to imagine a ecosystem that does allow limited, and secure transfer and/or copying of passkeys. DNS has such a system for example. Anyone can go buy a DNS name, then securely move it between all registrars. There could be a similar system for passkeys.

Passkeys have most of the bits in place. You need attestation, so whoever is relying on the key knows it's secure. The browsers could police attestation as they do now for CA's. We have secure devices that can be trusted to not leak leak passkeys in the form of phones, smartwatches, and hardware tokens. But we don't have a certification system for such devices. And we we don't have is a commercial ecosystem of companies willing to sell you safe passkey storage that allows copying to other such companies. On the technological front, we need standards for such storage, standards that ensure the companies holding the passkeys for you couldn't leak the secrets in the passkeys even if they were malicious.

We are at a frustrating point of being 80% of the way there, but the remaining 20% looks to be harder than the first 80%.