If you take account management and abstract account login and creation behind a sign in with Firefox button which would type in the password username or even create an account. You can start to manage login and add MFA to all sites add different levels of auth required to login to a site for example you may require a Fido token to login to your bank account but just click a button to login to your Reddit account. Also if there where finer account controls the user to delete an account from a dash board or have the password be changes automatic. Notes about the mess that is this block of text I tried to get every thing out that I had in my mind and did not do the best job so if you confused about this ask me a question
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