User visits wordpress.com/log-in and sees
"Or log in with your existing social profile:"
User thinks "Well I'll just click that. How simple!"
However if the user already has a Wordpress account that is not linked, this will just create an additional account!
One really cannot blame the user. He can't remember exactly which sites he has already linked to which accounts.
Anyway he now realizes he has created an additional account and starts to take steps to clean up his mistake.
Back on his original account, on https://wordpress.com/me/security/social-login when he tries to link it he will see
"This social account is already associated with a WordPress.com account."
He now needs to log back in to the new account via the same social login link.
Now in wordpress.com/me/security/social-login he needs to disconnect the social account.
Now he needs to login via username and password to his original account, (carefully avoiding the "Or log in with your existing social profile:") and in wordpress.com/me/security/social-login link his social account, so the problem won't occur in the future.
Also there is still the problem of deleting the second account... not an easy task...
My question is: can we really blame the user here?
Even if "existing social profile" was reworded "existing linked social profile" that wouldn't stop the problem.