> But once you get the response you can unblind the signed signature and obtain the token (which is just the unblinded signature).

The premise of this is to keep the person issuing the tokens and the person accepting them from correlating you.

The issue is when you have more than one service accepting them. You go to use Facebook and WhatsApp but they're both Meta so you present the same unblinded signature to both services and now your Facebook and WhatsApp accounts are correlated against your will. And they have a network that does the same thing, so you go to use a third party service and they require you to submit your unblinded signature to Meta which allows them to correlate you everywhere.