I don't want that either. Why should I tell google or github which sites I use... And tie also the accounts there to my google account.
Then use a password manager. Pick your poison.
Thats how we end up with apps without passeords, with just phone number/sms verification
But I get it. Maybe a throwaway email address is the right way around it for you?
If I set up foobarguy@gmail.com and use email verification because gmail requires me too, gmail can tie foobarguy@gmail.com to another email account.
But if I then use foorbarguy@gmail.com for $RANDOMFORUM, $RANDOMFORUM admin doesn't have any idea who I am. If they spam me or lose my password, I can just abandon foobarguy@gmail.com and set up barbazguy@gmail.com.
What am I missing?
Intense mistrust of google; a desire for the unattainable: true anonymity.