The server has all the inputs except the password and enough information to validate if it has guessed the right password. So password guessing/dictionary attac

The server has all the inputs except the password and enough information to validate if it has guessed the right password. So password guessing/dictionary attacks are still viable, especially with state level adversary. BUT users are given a false sense of security because "the password is never sent to the server". So we can expect users to (on average) use worse passwords and reuse passwords inappropriately. IMO, if you are going to use client certificates you should be just be using standard client certificates with whatever your OS provides to generate them.