Inazuma wrote:
It's just the ones that don't use text input boxes that don't I suppose.
This sites uses the U2F protocol and is not the same as the Yubikey OTP you use in text fields. The U2F protocol requires the browser to have access to you Yubikey device because U2F requires data to be sent into you Yubikey go get an answer.
The Yubikey OTP does not require any special access and is therefore implemented as a keyboard device which enters you OTP value into a text field when you touch you Yubikey.