Yes, OAuth2 is a toolkit that is open... for making proprietary non-interoptable auth solutions. One for each megacorp. That's why mail clients like Thunderbird

Yes, OAuth2 is a toolkit that is open... for making proprietary non-interoptable auth solutions. One for each megacorp. That's why mail clients like Thunderbird have a directory full of configuration scripts written specifically for each proprietary oauth2 solution made by each megacorp. Mail clients that do not go out of their way to support each corporation's unique out of band OAuth2 HTTPS solution are unable to access these oauth2 megacorp email accounts anymore (see gmail, office365, yahoo, etc). OAuth2 has made email servers proprietary. Simply supporting smtp or pop3 or imap is no longer sufficient. Custom HTTPS scripting has to be made for each corp and one corp's scripting won't work for another's login process. OAuth2 has been the email tower of babel.