That may be true, but changes nothing. People can share their credentials - doesn't mean having credentials is a bad thing.
They could clarify that you should protect your ID from the public, and perhaps give players the option to generate a new ID if it is accidentally revealed.
They could also ask for secondary info to verify an account holder further, but that is increasingly hard with all the data mining and info sharing sites available, which is why it is good to have a secret code that only the owner should know.
Ultimately, If the player ID cannot be used to recover a lost account, it serves no purpose and should be removed.
