I disagree somewhat that that is a "fumble" so much as a symptom of what was necessary to get mainstream acceptance, what a lot of us on HN see as "maximum vendor lock" is also an attempt at building a "pit of success" for average, "boring" users. An "Uncle Charlie" with an iPhone, an iPad, and a Mac that trusts Apple and was already using iCloud Keychain as their primary password manager is going to have an easy time with passkeys and is going to have a harder time accidentally enrolling a passkey they don't understand or know how to use the next time or next device they login from. That's a reasonable "pit of success" for an average, "boring" user.

There's a lot of users that isn't great for. Especially there are statistically a lot of iOS users that use Windows desktop/laptops that Microsoft and Apple are trying to bridge but don't always have the best UX today. Same for Android and Windows users, there's statistically even more of those.

Also, as you can tell from HN comments every time Passkeys come up, HN is full of anecdotes of the craziest mixed device ecosystems people can build. We can be a loud set of users, and we certainly need the most convincing that our "power user" needs are met for all of our complexity requirements.