[BeefWellington]

> A password manager only really offers marginal phishing protection, in the sense that 'automatic autofill' (as defined in the original post) is not available with an unrecognised website.

I don't know if alerting the user that something is wrong could be described as "marginal" for phishing attacks.

Sure, they may still make the bad decision but it might seem odd to them that their password manager didn't offer to fill it in for the site and get them to start looking around and double checking things.