Yubikey is here since 2007... and Windows 10 still doesn't support passwordless, security key only! login. They want you to register a goddamn MS account too...
Microsoft Outlook and live.com logins can use security keys, in fact they are accepted as a single authentication factor rather than a second one: supply your Yubikey and you're logged in without username or password!
However, Windows Hello in Windows 10 does not support local logins with security keys. This may have changed last week with a recent update, but it definitely wasn't supported when I installed Windows last Christmas.
I think it's Microsoft's opinion that security keys are too secure for consumer use; if a consumer is locked out of their personal device due to mismanagement, theft or loss of a hardware key, that's a support headache and liability burden that they're unwilling to take on at this point.
https://support.yubico.com/hc/en-us/articles/360013707820-Yu...