The request does not contain any information about the website that requires your age to be verified, but it is signed with a key associated with you (so, a key associated with the person whose age is to be verified). The point is that the e-ID service gets no information that identifies the website that requires your age to be verified; and at the same time that website gets no information about us, apart from whether or not we satisfy the age requirement. For example, if all social networks would be forced to implement age verification, the entity controlling the e-ID service could be able to maliciously block specific persons from accessing to them, or at least make it much more difficult for them – simply by refusing age verification requests coming from these persons.