If we think about real life, you need an identity for things like passports, state benefits and some other stuff but with normal things like shopping you don't need an ID at all.
So if I go to a shop and buy a tshirt then I have done that pretty much anonymously but if I buy on a website that requires a Facebook connect login then I have given way more information about myself.
So if I go to a shop and buy a tshirt then I have done that pretty much anonymously but if I buy on a website that requires a Facebook connect login then I have given way more information about myself.