[acdha]

Deterministic doesn't mean predictable by an attacker who can't read system memory but consider also that this could be implemented as simply as a cache: store the generated password for that hostname for n minutes and reuse it for autofill when present. There are a number of hokey things web developers do around security and this would seem like a good hedge against, for example, the ones who split the password and confirmation into separate forms or make you login to their related services because they haven't setup SSO properly.