The two "benefits", both of which I think are bullshit, are supposed to be: you know when masked passwords match, and you recognize that you've correctly typed your password in the future. The former case usually only happens for signup or password change, and is more easily, intuitively, and accessibly handled with explicit 'matches/doesn't match' symbols. The latter case (again, which I think is bullshit) would be completely obviated by your proposal.

This is just A Bad Idea.